Добрый день, Уважаемые Студенты!
Начинаем нашу рабочую неделю согласно следующего плана:
1) Test Grammar - материалы предоставляются на занятии
2) Text Book - https://www.ck12.org/book/CK-12-Chemistry-Intermediate/section/9.0/
Чтение, перевод, тесты после параграфов
3) Listening&Speaking - http://www.bbc.co.uk/learningenglish/english/features/6-minute-english/ep-190912
Ответить на вопросы до прослушивания, после прослушивания.
Начинаем нашу рабочую неделю согласно следующего плана:
1) Test Grammar - материалы предоставляются на занятии
2) Text Book - https://www.ck12.org/book/CK-12-Chemistry-Intermediate/section/9.0/
Чтение, перевод, тесты после параграфов
3) Listening&Speaking - http://www.bbc.co.uk/learningenglish/english/features/6-minute-english/ep-190912
Ответить на вопросы до прослушивания, после прослушивания.
Test -- 77%
ОтветитьУдалитьTest Grammar 92%
ОтветитьУдалить1.a ionic
Удалитьb molecular
c molecular
d ionic.
2. Covalent bond is a result of sharing valence electrons between two or more nonmetal atoms.
Ionic bound is a result of attraction between oppositely charged particles due to the electrostatic forces.
3.As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases.As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease. Eventually, a position is reached where the potential energy is at its lowest possible point. If the atoms move any closer together, the repulsive force between the two positively charged nuclei (a third type of interaction) begins to dominate. When like charges are forced this close together, the resulting repulsive force is very strong, as can be seen by the sharp rise in energy at the far left of the diagram.
4. In a single covalent bond 2 electrons are shared. In a double covalent bond 4 electrons are shared.In a single covalent bond 6 electrons are shared.
5.Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond. These two bonds are identical the properties of each bond are in between those expected for a single bond and a double bond between two oxygen atoms.
6 Beryllium, due to its small size and relatively high ionization energy (compared to other metals), forms primarily molecular compounds
Boron and aluminum, with three valence electrons.
There are a number of molecules whose total number of valence electrons is an odd number. It is not possible for all of the atoms in such a molecule to satisfy the octet rule. An example is nitrogen dioxide (NO2). Each oxygen atom contributes six valence electrons and the nitrogen atom contributes five, for a total of 17.
Starting with the third period, the d sublevel becomes available, so it is possible to use these orbitals in bonding, resulting in more than eight electrons around the central atom.
10. Carbon has 4 valence electrons, nitrogen and oxygen have 5 and 6 valence electrons respectively. When forming a covalent bond with a carbon atom nitrogen or oxygen carbon atom is unable to have an octet of electrons, so in order the molecule to be stable a nitrogen or an oxygen atom completely contributes one of its lone pairs to form an extra bond. But carbon atom has no lone pairs to contribute because all of its 4 valence electrons are involved in forming of the covalent bounds.
11. a, c, e.
Grammar 87%
ОтветитьУдалитьGrammar test 85%
ОтветитьУдалитьGrammar test 93%
ОтветитьУдалить1.ionic,molecular,molecular,ionic
ОтветитьУдалить2.The chemical bonding that occurs in molecular compounds is a sharing of valence electrons called covalent bonding. Covalent bonds occur primarily between nonmetal atoms.
Ionic compounds are crystalline in nature, but with alternating cations and anions held together by attractive electrostatic forces called ionic bonds.
3.As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases.As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease. Eventually, a position is reached where the potential energy is at its lowest possible point. If the hydrogen atoms move any closer together, the repulsive force between the two positively charged nuclei (a third type of interaction) begins to dominate. When like charges are forced this close together, the resulting repulsive force is very strong, as can be seen by the sharp rise in energy at the far left of the diagram.
4.2,4,6
5.Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond.
It was once thought that the structure of a molecule, such as O3, consisted of one single bond and one double bond that shifted rapidly back and forth, as shown above. However, further studies showed that the two bonds are identical. Additionally, the properties of each bond are in between those expected for a single bond and a double bond between two oxygen atoms.
6.Beryllium is an alkaline earth metal, so you might expect it to form ionic bonds. However, due to its small size and relatively high ionization energy (compared to other metals), beryllium forms primarily molecular compounds when combined with many other elements. Since beryllium only has two valence electrons, it does not typically attain a full octet by sharing electrons.
Boron and aluminum, with three valence electrons, also tend to have an incomplete octet when they form covalent compounds.
There are a number of molecules whose total number of valence electrons is an odd number. It is not possible for all of the atoms in such a molecule to satisfy the octet rule. An example is nitrogen dioxide (NO2). Each oxygen atom contributes six valence electrons and the nitrogen atom contributes five, for a total of 17.
Starting with the third period, the d sublevel becomes available, so it is possible to use these orbitals in bonding, resulting in more than eight electrons around the central atom.
10.This bonds is considered a coordinate covalent bond, which is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.
Grammar test: 80%
ОтветитьУдалитьTest 9.1
Удалить1. ionic,molecular,molecular,ionic
2. The chemical bonding that occurs in molecular compounds is a sharing of valence electrons called covalent bonding. Covalent bonds occur primarily between nonmetal atoms.
3. As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases. As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease.
4. 2, 4, 6
5. Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond.
6. Beryllium is an alkaline earth metal, so you might expect it to form ionic bonds. However, due to its small size and relatively high ionization energy (compared to other metals), beryllium forms primarily molecular compounds when combined with many other elements. Since beryllium only has two valence electrons, it does not typically attain a full octet by sharing electrons.
Boron and aluminum, with three valence electrons, also tend to have an incomplete octet when they form covalent compounds.
10. This bonds is considered a coordinate covalent bond, which is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.
Test 9.2
Удалить1. The molecular geometry, or shape, of a molecule is an important factor that affects the physical and chemical properties of a compound.
2. The molecular geometries of molecules change when the central atom has one or more lone pairs of electrons. The total number of electron pairs, both bonding pairs and lone pairs, leads to what is called the electron domain geometry.
3. The valence-shell electron pair repulsion model, or VSEPR model, states that a molecule will adjust its shape so that the valence electron pairs stay as far apart from each other as possible. This makes sense, based on the fact that negatively charged electrons repel one another. We will systematically classify molecules according to the number of bonding pairs of electrons and the number of nonbonding or lone pairs around the central atom.
4. a) 5
b) 4
c) 6
d)2
e) 3
f) 4
5. As for methane and ammonia, the domain geometry for a molecule with four electron pairs is tetrahedral. In the water molecule, two of the electron pairs are lone pairs rather than bonding pairs. The molecular geometry of the water molecule is referred to as bent. The H-O-H bond angle is 104.5°, which is smaller than the bond angle in NH3.
6. The Lewis structure for SF4 contains four single bonds and a lone pair on the sulfur atom. Because of the greater repulsion of a lone pair, it is one of the equatorial atoms that is replaced by a lone pair.
7. a) bent
b) trigonal planar
c) trigonal planar
d) see-saw
e) linear
8. a) trigonal planar
b) linear
c) trigonal pyramid
d) tetrahedral
e) trigonal bipyramidal
9. The geometry of the BH3 molecule is called trigonal planar. The hydrogen atoms are positioned at the vertices of an equilateral triangle. The H-B-H angle is 120°, and all four atoms lie in the same plane. In the molecule, one of the electron pairs is a lone pair rather than a bonding pair. The molecular geometry of AsH3 is called trigonal pyramidal. The H-As-H angle is approximately 107°.
10. The bond angle between the two pairs bonded with the central atom is 180 degrees, which makes the molecular geometry of XeF2 linear.
11. 42 valence electrons 8 valence electrons are coming from the xenon atom 6 valence electrons are coming from the oxygen atom 7 valence electrons from each of the four fluorine atoms. Answer: Square pyramidal.
Test 9.3
Удалить1. A bond with an electronegativity difference between 0.4 and 1.7 is called a polar covalent bond.
2. Diatomic molecules are molecules composed of two atoms of the same or different chemical elements.
3. The symbols δ+ and δ− in a structural formula of a molecule denotes an incomplete charge of an atom.
4. A molecule is called nonpolar if its complete charge equals to zero. It can contain polar covalent bonds, the only condition is an ideal molecular geometry (linear, trigonal, tetragonal, regular bipyramidal).
5. Van der Waals forces are the weakest intermolecular forces, Dipole-dipole forces are stronger and Hydrogen bond forces are the strongest intermolecular attractive forces.
6. For a molecule to undergo hydrogen bonding, it must have a hydrogen atom covalently bonded to an atom of fluorine, oxygen, or nitrogen.
7. Ionic compounds do not conduct electricity well in the solid state because of their rigid structures, but they conduct well when they are molten or dissolved in water, because they form movable charged particles in a liquid. Movable charged particles can conduct electricity.
8. Cl−F, P−H, Br−C, Al−N, K−O.
9. a) tetrahedral nonpolar
b) bent plane polar
c) trigonal plane nonpolar
d) trigonal pyramidal polar
e) tetragonal pyramidal polar
f) linear nonpolar
g) trigonal bipyramidal nonpolar
h) trigonal pyramidal polar
i) tetragonal bipyramidal nonpolar
10. ICl < Br2
HCl < HF
Kr > Ar
CF4 > CH4
NH3 < PH3
11. Ethanol molecules form hydrogen bonds because they have a hydrogen atom connected to the oxygen atom. Dimethyl molecules don't have OH- groups, so they can't form hydrogen bonds.
Test 9.4
Удалить1. Valence bond theory states that covalent bonds are formed by the overlap of partially filled atomic orbitals.
2. Hybridization is the mixing of the atomic orbitals in an atom to produce a set of hybrid orbitals. When hybridization occurs, it must do so as a result of the mixing of nonequivalent orbitals.
3. a) sp
b) sp3
c) sp3d2
d) sp2
e) sp3d
4. An optimum distance between the two nuclei, equal to the bond length, is eventually attained, and the potential energy reaches a minimum. At this point, a stable single covalent bond has formed between the two hydrogen atoms. Other covalent bonds form in the same way as unpaired electrons from two atoms “match up” to form the bond. In a fluorine atom, there is an unpaired electron in one of the 2p orbitals. When a F2 molecule forms, the 2p orbitals from each of the two atoms overlap to produce the F−F covalent bond. The overlapping orbitals do not have to be of the same type.
5. a) 120
b) different
c) 180
d) 109,5
6. A sigma bond is a bond formed by the overlap of orbitals in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms. A pi bond is a bond formed by the overlap of orbitals in a side-by-side fashion, with the electron density concentrated above and below the plane of the nuclei of the bonding atoms.
7. a) sigma bond
b) sp
c) sigma-pi bond
8. There are 10 sigma bonds and 3 pi bonds in this molecule.
9. a) linear, sp
b) trigonal pyramidal, sp3
c) trigonal plane, sp2
d) tetragonal pyramidal, sp3d
e) octahedral, sp3d2
f) linear, sp3d2
g) tetragonal bipyramidal, sp3d2
h) bent plane, sp2
i) tetrahedral, sp3
Listening
УдалитьI think that tourism is a wonderful chance to become acquainted with different places and countries. It can be rather harmful, if a person doesn't want to lead the rules of the certain country. Because sometimes natives don't tolerate bad attitudes towards themselves and their country.
Listening
УдалитьSometimes tourism can be harmful. For example, Romans don't like to see tourists walking around bare-chested, they don't like to see them wading in their fountains. The authorities in the city fear that some tourists are showing disrespect to the city and have introduced laws to clampdown on certain behaviour.
Алимханова
ОтветитьУдалитьGrammar test - 84%
Алимханова
ОтветитьУдалитьPart 1.
1. ionic, molecular, molecular, ionic.
2. The chemical bonding that occurs in molecular compounds is a sharing of valence electrons called covalent bonding. Covalent bonds occur primarily between nonmetal atoms.
Ionic compounds are crystalline in nature, but with alternating cations and anions held together by attractive electrostatic forces called ionic bonds.
3. As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases.As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease. Eventually, a position is reached where the potential energy is at its lowest possible point. If the hydrogen atoms move any closer together, the repulsive force between the two positively charged nuclei (a third type of interaction) begins to dominate. When like charges are forced this close together, the resulting repulsive force is very strong, as can be seen by the sharp rise in energy at the far left of the diagram.
4. 2, 4, 6.
5. Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond. It was once thought that the structure of a molecule, such as O3, consisted of one single bond and one double bond that shifted rapidly back and forth, as shown above. However, further studies showed that the two bonds are identical. Additionally, the properties of each bond are in between those expected for a single bond and a double bond between two oxygen atoms.
6. Beryllium is an alkaline earth metal, so you might expect it to form ionic bonds. However, due to its small size and relatively high ionization energy (compared to other metals), beryllium forms primarily molecular compounds when combined with many other elements. Since beryllium only has two valence electrons, it does not typically attain a full octet by sharing electrons.
Boron and aluminum, with three valence electrons, also tend to have an incomplete octet when they form covalent compounds. There are a number of molecules whose total number of valence electrons is an odd number. It is not possible for all of the atoms in such a molecule to satisfy the octet rule. An example is nitrogen dioxide (NO2). Each oxygen atom contributes six valence electrons and the nitrogen atom contributes five, for a total of 17. Starting with the third period, the d sublevel becomes available, so it is possible to use these orbitals in bonding, resulting in more than eight electrons around the central atom.
7. В тетради
8. В тетради
9. В тетради
10.This bonds is considered a coordinate covalent bond, which is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.
11. a, c, e.
12. В тетради.
Алимханова
УдалитьPart 2.
1. The molecular geometry, or shape, of a molecule is an important factor that affects the physical and chemical properties of a compound.
2. The molecular geometries of molecules change when the central atom has one or more lone pairs of electrons. The total number of electron pairs, both bonding pairs and lone pairs, leads to what is called the electron domain geometry.
3. The valence-shell electron pair repulsion model, or VSEPR model, states that a molecule will adjust its shape so that the valence electron pairs stay as far apart from each other as possible. This makes sense, based on the fact that negatively charged electrons repel one another. We will systematically classify molecules according to the number of bonding pairs of electrons and the number of nonbonding or lone pairs around the central atom.
4. a 5
b 4
c 6
d 2
e 3
f 4
5. As for methane and ammonia, the domain geometry for a molecule with four electron pairs is tetrahedral. In the water molecule, two of the electron pairs are lone pairs rather than bonding pairs. The molecular geometry of the water molecule is referred to as bent. The H-O-H bond angle is 104.5°, which is smaller than the bond angle in NH3.
6. The Lewis structure for SF4 contains four single bonds and a lone pair on the sulfur atom. Because of the greater repulsion of a lone pair, it is one of the equatorial atoms that is replaced by a lone pair.
7. a. bent
b. trigonal planar
c. trigonal planar
d. See-saw
e. Linear
8. a. trigonal planar
b. linear
c. trigonal pyramid
d. tetrahedral
e. trigonal bipyramidal
9. The geometry of the BH3 molecule is called trigonal planar. The hydrogen atoms are positioned at the vertices of an equilateral triangle. The H-B-H angle is 120°, and all four atoms lie in the same plane. In the molecule, one of the electron pairs is a lone pair rather than a bonding pair. The molecular geometry of AsH3 is called trigonal pyramidal. The H-As-H angle is approximately 107°.
10. The bond angle between the two pairs bonded with the central atom is 180 degrees, which makes the molecular geometry of XeF2 linear.
11. 42 valence electrons 8 valence electrons are coming from the xenon atom 6 valence electrons are coming from the oxygen atom 7 valence electrons from each of the four fluorine atoms. Answer: Square pyramidal.
Алимханова
УдалитьPart 3.
1. A bond in which the electronegativity difference between the atoms is between 0.4 and 1.7 is called a polar covalent bond.
2. Diatomic molecules are molecules composed of only two atoms, of the same or different chemical elements. For example N2 or HF.
3. An easy way to illustrate the uneven electron distribution in a polar covalent bond is to use the Greek letter, delta (δ) along with a positive or negative sign to indicate that an atom has a partial positive or negative charge. The delta symbol is used to indicate that the quantity of charge is less than one.
4. For molecules with more than two atoms, the molecular geometry must also be taken into account when determining if the molecule is polar or nonpolar. Carbon dioxide (CO2) is a linear molecule. The oxygen atoms are more electronegative than the carbon atom, so there are two individual dipoles pointing outward from the C atom to each O atom. However, since the dipoles are of equal strength and are oriented in this way, they cancel each other out, and the overall molecular polarity of CO2 is zero.
5. Van der Waals forces are the weakest intermolecular force and consist of dipole-dipole forces and dispersion forces. Dispersion forces are also considered a type of van der Waals force and are the weakest of all intermolecular forces. London dispersion forces are intermolecular forces that occur between all atoms and molecules due to the random motion of electrons. Dipole-dipole forces are the attractive forces that occur between polar molecules. A hydrogen bond is an intermolecular attractive force in which a hydrogen atom, that is covalently bonded to a small, highly electronegative atom, is attracted to a lone pair of electrons on an atom in a neighboring molecule. Hydrogen bonds are very strong compared to other dipole-dipole interactions.
6. Hydrogen bonding occurs only in molecules where hydrogen is covalently bonded to one of three elements: fluorine, oxygen, or nitrogen. These three elements are so electronegative that they withdraw the majority of the electron density from the covalent bond with hydrogen, leaving the H atom very electron-deficient. Because the hydrogen atom does not have any electrons other than the ones in the covalent bond, its positively charged nucleus is almost completely exposed, allowing strong attractions to other nearby lone pairs.
7. The energy required to disrupt the intermolecular forces between molecules is far less than the energy required to break the ionic bonds in a crystalline ionic compound. Since molecular compounds are composed of neutral molecules, their electrical conductivity is generally quite poor, whether in the solid or liquid state. Ionic compounds do not conduct electricity well in the solid state because of their rigid structures, but they conduct well when they are molten (in the liquid state) or dissolved in water. The water solubility of molecular compounds is variable and depends primarily on the type of intermolecular forces involved.
8. P-H (0,01), Br-C (0.41), Cl-F (0.82), Al-N (1.43), K−O (2.62).
9. a. tetrahedral, nonpolar
b. bent, nonpolar
c. trigonal planar, nonpolar
d. trigonal pyramid, polar
e. trigonal bipyramid, polar
f. linear, nonpolar
g. T-shaped, polar
h. tetrahedral, polar
i. octahedral, nonpolar
10. a. ICl b. HF c. Kr d. CF4 e. NH3
Therefore, a comparison of boiling points is essentially equivalent to comparing the strengths of the attractive intermolecular forces exhibited by the individual molecules.
11. Ethanol contains hydrogen atoms that are bound to a highly electronegative oxygen atom, making for very polar bonds. Hydrogen bonds are very strong compared to other dipole-dipole interactions. A comparison of boiling points is essentially equivalent to comparing the strengths of the attractive intermolecular forces exhibited by the individual molecules.
Алимханова
УдалитьPart 4
1. Valence bond theory states that covalent bonds are formed by the overlap of partially filled atomic orbitals
2. Hybridization of atomic orbitals is the mixing of the atomic orbitals in an atom to produce a set of hybrid orbitals.
3. a. sp
b. sp3
c. sp3d2
d. sp2
e. sp3d
4. No. They are the same in energy, so it would lose the point to hybridize them. They have no necessity to hybridize with other orbitals.
5. a. 180
b. ≈107-109
c. 90
d. 120
e. 90 and 120
6. A sigma bond (σ bond) is a bond formed by the overlap of orbitals in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms. A pi bond (π bond) is a bond formed by the overlap of orbitals in a side-by-side fashion, with the electron density concentrated above and below the plane of the nuclei of the bonding atoms.
7. a. All of orbitals have a compatible partner: 4px with 4px, 4py with 4py, etc. Each bromine would donate one 4pz electron to form a σ-bonding orbital. Hybridization of the molecule Br2 is sp3
b. Hybridization of the molecule H2S is sp3. the Sulfur atom is in center bonding with two Hydrogen atoms forming the bond.
c. It has a triple bond and one lone pair on each nitrogen atom. When determining hybridization, you must count the regions of electron density. Since there are only two regions of electron density (1 triple bond + 1 lone pair), the hybridization must be sp.
8. a. sp, sp, sp3, sp2
b. 10 sigma bonds, 3 pi bonds.
9. a. linear, sp, linear
b. tetrahedral, sp3, trigonal pyramid
c. trigonal planar, sp2, trigonal planar
d. trigonal bipyramidal, sp3, seesaw
e. octahedral, sp3d2, square planar
f. trigonal bipyramidal, sp3, linear
g. octahedral, sp3d, square pyramidal,
h. trigonal planar, sp2, bent
i. tetrahedral, sp3, bent.
Grammar 82%
ОтветитьУдалитьReading test 1
ОтветитьУдалить1. CaBr2 - ionic
PCl3 - molecular
H2S - molecular
ZnO - ionic
2. An ionic bond forms when one of the atoms completely gives his electron to another. A covalent bond forms when two atoms share the mutual pare of electrones.
3. As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases. As the two atoms move closer and closer together, the potential energy continues to decrease. Eventually, a position is reached where the potential energy is at its lowest possible point. If atoms move any closer together, the repulsive force between the their positively charged nuclei (a third type of interaction) begins to dominate. When like charges are forced this close together, the resulting repulsive force is very strong and potential energy sharply increase.
4. Two electrons are shared between atoms in a single covalent bond, four in a double covalent bond and six in a triple covalent bond.
5. Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond. It was once thought that the structure of a molecule, such as O3, consisted of one single bond and one double bond that shifted rapidly back and forth, as shown above. However, further studies showed that the two bonds are identical. Additionally, the properties of each bond are in between those expected for a single bond and a double bond between two oxygen atoms.
6. Starting with the third period, the d sublevel becomes available, so it is possible to use these orbitals in bonding, resulting in more than eight electrons around the central atom.
7. Задание для письменного выполнения в тетради.
8. Задание для письменного выполнения в тетради.
9. Задание для письменного выполнения в тетради.
10. Coordinate covalent bond is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair. Oxygen and nitrogen atoms can form a coordinate C-O and C-N bond, because they have lone electron pairs. Hydrogen and carbon atoms in C-H and C-C bonds don't have lone pairs, so they don't form a coordinate bond.
11. AlH3, BeCl2 and NO do not follow the octet rule.
12. Задание для письменного выполнения в тетради.
Test 2
Удалить1. Because the molecular geometry, or shape, of a molecule is an important factor that affects the physical and chemical properties of a compound.
2. The total number of electron pairs, both bonding pairs and lone pairs, leads to what is called the electron domain geometry. Electron domain geometries are one of the five learned so far: linear, trigonal planar, tetrahedral, trigonal bipyramidal, or octahedral. However, when one or more of the bonding pairs of electrons is replaced with a lone pair, the molecular geometry, or actual shape of the molecule, is altered.
(NH3 and CH4 both have a tetrahedral electron domain, but CH4 is a real tetrahedr while NH3 is just a pyramid)
3. In terms of its effect on molecular geometry, how does the repulsion from a lone pair of electrons compare to the repulsion from a bonding pair of electrons?
4. trigonal bipyramidal (5)
tetrahedral (4)
octahedral (6)
bent (2)
trigonal pyramidal (3)
square planar (4)
5. Because the third hydrogen atom in NH3 molecule produce an additional repulsing forse that repulses other two atoms to a bigger angle.
6. Sulfur atom in an SF4 molecule has one lone electron pair that distortes the molecule geometry.
7. SF2 -- bent planar
PBr3 -- trigonal pyramidal
AlCl3 -- planar trigonal
TeCl4 -- tetrahedral
HCN -- linear
8. NO3− trigonal planar
ICl2− bent planar
ClO3− trigonal planar
PO43− tetrahedral
SeCl3− trigonal pyramidal
9. AsH3 molecule adopts a trigonal pyramidal geometry, it would be reasonably to guess that AsH3 has the same angle (~107°) as NH3 molecule which has the same structure and because As belongs to the same period that N. The angle will be a little bit bigger than in NH3 because arsenic atom has a bigger radius than a nitrogen atom that causes less repulsive forse between hydrogen atoms.
BH3 molecule adopts a trigonal pyramidal geometry, so it will has a typical 120° angle.
10. XeF2 molecule conteins three lone pairs. It will be stable with trigonal bipyramidal geometry and an angle of 180° between fluorine atoms.
11. Geometry of the XeOF4 molecule will be distorted tetragonal bipyramidal with angles of 90° between four fluorine atoms.
Test 3
Удалить1. A bond whith an electronegativity difference between 0.4 and 1.7 is called a polar covalent bond.
2. Diatomic molecules are molecules composed of two atoms of the same or different chemical elements.
3. The symbols δ+ and δ− in a structural formula of a molecule denotes an incomplete charge of an atom.
4. A molecule is called nonpolar if its complete charge equales to zero. It can contain polar covalent bonds, the only condition is an ideal molecular geometry (linear, trigonal, tetragonal, regular bipyramidal).
5. Van der Waals forces are the weakest intermolecular forces, Dipole-dipole forces are stronger and Hydrogen bond forces are the strongest intermolecular attractive forces.
6. For a molecule to undergo hydrogen bonding, it must have a hydrogen atom covalently bonded to an atom of fluorine, oxygen, or nitrogen.
7. Ionic compounds do not conduct electricity well in the solid state because of their rigid structures, but they conduct well when they are molten or dissolved in water, because they form movable charged particles in a liquid. Movable charged particles can conduct electricity.
8. Cl−F, P−H, Br−C, Al−N, K−O.
9. CBr4 — tetrahedral nonpolar
H2S -- bent plane polar
BF3 -- trigonal plane nonpolar
PCl3 -- trigonal pyramidal polar
SeF4 -- tetragonal pyramidal polar
BeCl2 -- linear nonpolar
ClF3 -- trigonal bipyramidal nonpolar
CH2Cl2 -- trigonal pyramidal polar
SF6 -- tetragonal bipyramidal nonpolar
10. ICl < Br2
HCl < HF
Kr > Ar
CF4 > CH4
NH3 < PH3
11. Ethanol molecules form hydrogen bonds because they have a hydrogen atom connected to the oxygen atom. Dimethyl molecules don't have OH- groupes, so they can't form hydrogen bonds.
1. Valence bond theory states that covalent bonds are formed by the overlap of partially filled atomic orbitals
Удалить2. Hybridization of atomic orbitals is the mixing of the atomic orbitals in an atom to produce a set of hybrid orbitals.
3. linear -- sp
tetrahedral -- sp3
octahedral -- sp3d2
trigonal planar -- sp2
trigonal bipyramidal -- sp3d
4. Two 2p orbitals of an atom can't hybridize because hybridization occures only with different types of orbitals.
5. sp2 -- 120
sp3d2 -- different
sp -- 180
sp3 -- 109.5
6. A sigma bond (σ bond) is a bond formed by the overlap of orbitals in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms. A pi bond (π bond) is a bond formed by the overlap of orbitals in a side-by-side fashion, with the electron density concentrated above and below the plane of the nuclei of the bonding atoms.
7. Br2 -- sigma p-p bond
H2S -- two sigma p-s bonds
N2 -- one sigma p-p and two pi p-p bonds
8. A. Задание для письменного выполнения в тетради.
B. There are 10 sigma bonds and 3 pi bonds in this molecule.
9. CS2 -- linear sp
PCl3 -- trigonal pyramidal sp3
COCl2 -- trigonal plane sp2
SeF4 -- tetragonal pyramidal sp3d
ICl4− -- octahedral sp3d2
KrF2 -- linear sp3d2
XeOF4 -- tetragonal bipyramidal sp3d2
SO2 -- bent plane sp2
OF2 -- tetrahedral sp3
1.The molecular geometry, or shape, of a molecule is an important factor that affects the physical and chemical properties of a compound. Those properties include melting and boiling points, solubility, density, and the types of chemical reactions that a compound undergoes.
ОтветитьУдалить2.Molecular geometry is the three-dimensional arrangement of atoms in a molecule. The total number of electron pairs, both bonding pairs and lone pairs, leads to what is called the electron domain geometry. Electron domain geometries are one of the five learned so far: linear, trigonal planar, tetrahedral, trigonal bipyramidal, or octahedral. However, when one or more of the bonding pairs of electrons is replaced with a lone pair, the molecular geometry, or actual shape of the molecule, is altered.
3.The valence shell is the outermost occupied shell of electrons in an atom. This shell holds the valence electrons, which are the electrons that are involved in bonding and shown in a Lewis structure.The valence-shell electron pair repulsion model, or VSEPR model, states that a molecule will adjust its shape so that the valence electron pairs stay as far apart from each other as possible. This makes sense, based on the fact that negatively charged electrons repel one another.
4.a.5
b.4
c.6
d.2
e.3
f.4
5.As for methane and ammonia, the domain geometry for a molecule with four electron pairs is tetrahedral. In the water molecule, two of the electron pairs are lone pairs rather than bonding pairs. The molecular geometry of the water molecule is referred to as bent. The H-O-H bond angle is 104.5°, which is smaller than the bond angle in NH3.
6.The Lewis structure for SF4 contains four single bonds and a lone pair on the sulfur atom.Because of the greater repulsion of a lone pair, it is one of the equatorial atoms that is replaced by a lone pair. The geometry of the molecule is called a distorted tetrahedron or seesaw.
7.a.bent
b.trigonal planar
c.trigonal planar
d.seesaw
e.linear
8.a.trigonal planar
b.linear
c.trigonal pyramide
d.tetrahedral
e.trigonal bipyramide
9.The geometry of the BH3 molecule is called trigonal planar. The fluorine atoms are positioned at the vertices of an equilateral triangle. The H-B-H angle is 120°, and all four atoms lie in the same plane.
The domain geometry for a molecule with four electron pairs is tetrahedral, as was seen with CH4. In the AsH3 molecule, one of the electron pairs is a lone pair rather than a bonding pair. The molecular geometry of NH3 is called trigonal pyramidal.(107°).
10.trigonal bipyramidal domain geometry,linear molecular geometry
11.octahedral domain geometry,square pyramidal
Test 9.1
ОтветитьУдалить1. Ionic, molecular, molecular, ionic
2. The chemical bonding that occurs in molecular compounds is a sharing of valence electrons called covalent bonding. Covalent bonds occur primarily between nonmetal atoms.
3. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases.
4. 2,4,6
5. Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond.
6. Elements of the third period and beyond are capable of exceeding the octet rule.
10. This bonds is considered a coordinate covalent bond, which is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.
Grammar test-84%
ОтветитьУдалитьGrammar test - 93%
ОтветитьУдалить1. Ionic, molecular, molecular, ionic
ОтветитьУдалить2. The chemical bonding that occurs in molecular compounds is a sharing of valence electrons called covalent bonding. Covalent bonds occur primarily between nonmetal atoms. Ionic compounds are also crystalline in nature, but with alternating cations and anions held together by attractive electrostatic forces called ionic bonds.
3. As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. However, attractive forces also begin to develop between each electron and the positively charged nucleus of the other atom, causing a decrease in potential energy. As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease. Eventually, a position is reached where the potential energy is at its lowest possible point. When like charges are forced this close together, the resulting repulsive force is very strong, as can be seen by the sharp rise in energy at the far left of the diagram.
4. 2, 4, 6
5. It was once thought that the structure of a molecule, such as O3, consisted of one single bond and one double bond that shifted rapidly back and forth, as shown above. However, further studies showed that the two bonds are identical. Additionally, the properties of each bond are in between those expected for a single bond and a double bond between two oxygen atoms. For example, a double covalent bond between two given atoms is typically stronger and shorter than a single covalent bond between those two atoms. Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond.
6. Beryllium is an alkaline earth metal, so you might expect it to form ionic bonds. However, due to its small size and relatively high ionization energy (compared to other metals), beryllium forms primarily molecular compounds when combined with many other elements. Since beryllium only has two valence electrons, it does not typically attain a full octet by sharing electrons. The Lewis structure of gaseous beryllium hydride (BeH2) consists of two single covalent bonds between Be and two H atoms. Boron and aluminum, with three valence electrons, also tend to have an incomplete octet when they form covalent compounds. The central boron atom in boron trichloride (BCl3) has six valence electrons as shown below. There are a number of molecules whose total number of valence electrons is an odd number. An example is nitrogen dioxide (NO2).
10. This bonds is considered a coordinate covalent bond, which is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.
1.A bond in which the electronegativity difference between the atoms is between 0.4 and 1.7 is called a polar covalent bond. A polar covalent bond is a covalent bond in which the atoms have an unequal attraction for electrons, so the sharing is unequal. In a polar covalent bond, sometimes simply called a polar bond, the distribution of shared electrons within the molecule is no longer symmetrical.
ОтветитьУдалить2.Any diatomic molecule in which the two atoms are the same element must be joined by a nonpolar covalent bond.There are seven diatomic elements, which are elements whose natural form is of a diatomic molecule. They are hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine. By forming a diatomic molecule, both atoms in each of these molecules satisfy the octet rule, resulting in a structure that is much more stable than the isolated atoms.
3.An easy way to illustrate the uneven electron distribution in a polar covalent bond is to use the Greek letter, delta (δ) along with a positive or negative sign to indicate that an atom has a partial positive or negative charge.The atom with the greater electronegativity acquires a partial negative charge, while the atom with the lesser electronegativity acquires a partial positive charge. The delta symbol is used to indicate that the quantity of charge is less than one. A crossed arrow can also be used to indicate the direction of greater electron density.
4.Yes.For example,carbon dioxide (CO2) is a linear molecule. The oxygen atoms are more electronegative than the carbon atom, so there are two individual dipoles pointing outward from the C atom to each O atom. However, since the dipoles are of equal strength and are oriented in this way, they cancel each other out, and the overall molecular polarity of CO2 is zero.
5.Van der Waals forces are the weakest intermolecular force and consist of dipole-dipole forces and dispersion forces.
Dipole-dipole forces are the attractive forces that occur between polar molecules.
London dispersion forces are intermolecular forces that occur between all atoms and molecules due to the random motion of electrons.
A hydrogen bond is an intermolecular attractive force in which a hydrogen atom, that is covalently bonded to a small, highly electronegative atom, is attracted to a lone pair of electrons on an atom in a neighboring molecule. Hydrogen bonds are very strong compared to other dipole-dipole interactions. A typical hydrogen bond is about 5% as strong as a covalent bond.
6.Hydrogen bonding occurs only in molecules where hydrogen is covalently bonded to one of three elements: fluorine, oxygen, or nitrogen. These three elements are so electronegative that they withdraw the majority of the electron density from the covalent bond with hydrogen, leaving the H atom very electron-deficient. Because the hydrogen atom does not have any electrons other than the ones in the covalent bond, its positively charged nucleus is almost completely exposed, allowing strong attractions to other nearby lone pairs.
7.Since molecular compounds are composed of neutral molecules, their electrical conductivity is generally quite poor, whether in the solid or liquid state. Ionic compounds do not conduct electricity well in the solid state because of their rigid structures, but they conduct well when they are molten (in the liquid state) or dissolved in water.
8.P-H,Br-C,Cl-F,Al-N,K-O
9.a.tetrahedral,nonpolar
b.bond,polar
c.tetrahedral,nonpolar
d.trigonal pyramid,polar
e.trigonal bipyramide, polar
f.linear,nonpolar
g.trigonal bipyramide, polar
h.tetrahedral,nonpolar
i.octahedral,nonpolar
10.In order for a substance to enter the gas phase, its particles must completely overcome the intermolecular forces holding them together. Therefore, a comparison of boiling points is essentially equivalent to comparing the strengths of the attractive intermolecular forces exhibited by the individual molecules. For small molecular compounds, London dispersion forces are the weakest intermolecular forces. Dipole-dipole forces are somewhat stronger, and hydrogen bonding is a particularly strong form of dipole-dipole interaction. However, when the mass of a nonpolar molecule is sufficiently large, its dispersion forces can be stronger than the dipole-dipole forces in a lighter polar molecule.
Удалитьa.Br2b.HClc.Ard.CH4e.PH3
11.The physical state and properties of a particular compound depend largely on the type of chemical bonding it displays. Molecular compounds, sometimes called covalent compounds, display a wide range of physical properties due to the different types of intermolecular attractions discussed in this lesson. The melting and boiling points of molecular compounds are generally quite low compared to those of ionic compounds. This is because the energy required to disrupt the intermolecular forces between molecules is far less than the energy required to break the ionic bonds in a crystalline ionic compound.
1.Any covalent bond results from the overlap of atomic orbitals. This idea forms the basis for a quantum mechanical theory called valence bond (VB) theory. Valence bond theory states that covalent bonds are formed by the overlap of partially filled atomic orbitals.
ОтветитьУдалить2.Hybridization is the mixing of the atomic orbitals in an atom to produce a set of hybrid orbitals. When hybridization occurs, it must do so as a result of the mixing of nonequivalent orbitals. For example, s and p orbitals can hybridize, but p orbitals cannot hybridize with other p orbitals. Hybrid orbitals are the atomic orbitals obtained when two or more nonequivalent orbitals from the same atom combine in preparation for bond formation.
3.sp,sp3,sp3d2,sp2,sp3d
4.In a fluorine atom, there is an unpaired electron in one of the 2p orbitals. When a F2 molecule forms, the 2p orbitals from each of the two atoms overlap to produce the F−F covalent bond. The overlapping orbitals however do not have to be of the same type.
5.120,90,180, 190,5
6.A sigma bond (σ bond) is a bond formed by the overlap of orbitals in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms. A pi bond (π bond) is a bond formed by the overlap of orbitals in a side-by-side fashion, with the electron density concentrated above and below the plane of the nuclei of the bonding atoms.
7.sigma bond,sp3,sigma-pi bond
8.3 pi-bonds,10 sigma-bonds
Test-75%
ОтветитьУдалитьTest 1
Удалить1.ionic,molecular,molecular,ionic
2.Covalent bond is a result of sharing valence electrons between two or more nonmetal atoms.
Ionic bound is a result of attraction between oppositely charged particles due to the electrostatic forces
3.As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases.As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease. Eventually, a position is reached where the potential energy is at its lowest possible point. If the hydrogen atoms move any closer together, the repulsive force between the two positively charged nuclei (a third type of interaction) begins to dominate. When like charges are forced this close together, the resulting repulsive force is very strong, as can be seen by the sharp rise in energy at the far left of the diagram.
4. Two electrons are shared between atoms in a single covalent bond, four in a double covalent bond and six in a triple covalent bond.
5Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond.It was once thought that the structure of a molecule, such as O3, consisted of one single bond and one double bond that shifted rapidly back and forth, as shown above. However, further studies showed that the two bonds are identical. Additionally, the properties of each bond are in between those expected for a single bond and a double bond between two oxygen atoms.
6. Beryllium is an alkaline earth metal, so you might expect it to form ionic bonds. However, due to its small size and relatively high ionization energy (compared to other metals), beryllium forms primarily molecular compounds when combined with many other elements. Since beryllium only has two valence electrons, it does not typically attain a full octet by sharing electrons. The Lewis structure of gaseous beryllium hydride (BeH2) consists of two single covalent bonds between Be and two H atoms. Boron and aluminum, with three valence electrons, also tend to have an incomplete octet when they form covalent compounds. The central boron atom in boron trichloride (BCl3) has six valence electrons as shown below. There are a number of molecules whose total number of valence electrons is an odd number. An example is nitrogen dioxide (NO2).
10.This bonds is considered a coordinate covalent bond, which is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.
Test 2
Удалить1.The molecular geometry, or shape, of a molecule is an important factor that affects the physical and chemical properties of a compound.
2.The molecular geometries of molecules change when the central atom has one or more lone pairs of electrons. The total number of electron pairs, both bonding pairs and lone pairs, leads to what is called the electron domain geometry. Electron domain geometries are one of the five learned so far: linear, trigonal planar, tetrahedral, trigonal bipyramidal, or octahedral.
3.The valence shell is the outermost occupied shell of electrons in an atom. This shell holds the valence electrons, which are the electrons that are involved in bonding and shown in a Lewis structure.The valence-shell electron pair repulsion model, or VSEPR model, states that a molecule will adjust its shape so that the valence electron pairs stay as far apart from each other as possible. This makes sense, based on the fact that negatively charged electrons repel one another.
4.a.5
b.4
c.6
d.2
e.3
f.4
5.As for methane and ammonia, the domain geometry for a molecule with four electron pairs is tetrahedral. In the water molecule, two of the electron pairs are lone pairs rather than bonding pairs. The molecular geometry of the water molecule is referred to as bent. The H-O-H bond angle is 104.5°, which is smaller than the bond angle in NH3.
6.he Lewis structure for SF4 contains four single bonds and a lone pair on the sulfur atom.Because of the greater repulsion of a lone pair, it is one of the equatorial atoms that is replaced by a lone pair.
7.a.bent
b.trigonal planar
c.trigonal planar
d.seesaw
e.linear
8.a.trigonal planar.
b.linear
c.trigonal pyramide
d.tetrahedral
e.trigonal bipyramide
9. AsH3 molecule adopts a trigonal pyramidal geometry, it would be reasonably to guess that AsH3 has the same angle (~107°) as NH3 molecule which has the same structure and because As belongs to the same period that N. The angle will be a little bit bigger than in NH3 because arsenic atom has a bigger radius than a nitrogen atom that causes less repulsive forse between hydrogen atoms.
BH3 molecule adopts a trigonal pyramidal geometry, so it will has a typical 120° angle.
10.It will be stable with trigonal bipyramidal geometry and an angle of 180° between fluorine atoms.
11.It will be distorted tetragonal bipyramidal with angles of 90° between four fluorine atoms.
Test 3
Удалить1. A bond with an electronegativity difference between 0.4 and 1.7 is called a polar covalent bond.
2. Diatomic molecules are molecules composed of only two atoms, of the same or different chemical elements. For example N2 or HF.
3. The symbols δ+ and δ− in a structural formula of a molecule denotes an incomplete charge of an atom.
4.Yes. The polar bonds can cancel each other out if arranged symmetrically around the center atom, Carbon dioxide is an example.
5.Van der Waals forces are the weakest intermolecular force and consist of dipole-dipole forces and dispersion forces. Dispersion forces are also considered a type of van der Waals force and are the weakest of all intermolecular forces. London dispersion forces are intermolecular forces that occur between all atoms and molecules due to the random motion of electrons. Dipole-dipole forces are the attractive forces that occur between polar molecules. A hydrogen bond is an intermolecular attractive force in which a hydrogen atom, that is covalently bonded to a small, highly electronegative atom, is attracted to a lone pair of electrons on an atom in a neighboring molecule. Hydrogen bonds are very strong compared to other dipole-dipole interactions..
6. oxygen or nitrogen
7.Molecular compounds are composed of neutral molecules, which are incapable of conducting a current.The ions in an ionic compound are charged particles and can conduct electricity as long as they are not held in place in a solid crystal.
8.P-H <Br-C <CI-F <Al-N <K-0
9. tetrahedral -nonpolar b. bent -polar c. trigonal planar -nonpolar d. trigonal pyramidal -polar e. seesaw -polar f. linear -nonpolar g. T-shaped polar h. tetrahedral -polar i. octahedral -nonpolar
11. Ethanol can hydrogen bond, while dimethyl ether cannot. In ethanol, one of the hydrogen atoms is bonded to the oxygen atom. The oxygen atom in dimethyl ether is only to two carbon atoms.
Test 4
Удалить1. Valence bond theory states that covalent bonds are formed by the overlap of partially filled atomic orbitals.
2. Hybridization is the mixing of the atomic orbitals in an atom to produce a set of hybrid orbitals. When hybridization occurs, it must do so as a result of the mixing of nonequivalent orbitals.
3. a) sp
b) sp3
c) sp3d2
d) sp2
e) sp3d
4. No. They are the same in energy, so it would lose the point to hybridize them. They have no necessity to hybridize with other orbitals.
5.sp2 - 120
sp3d2 - different
sp - 180
sp3 — 109.5
6. A sigma bond (σ bond) is a bond formed by the overlap of orbitals in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms. A pi bond (π bond) is a bond formed by the overlap of orbitals in a side-by-side fashion, with the electron density concentrated above and below the plane of the nuclei of the bonding atoms.
7.a.sigma bond
b.sp
c.sigma-pi bond
8.There are 10 sigma bonds and 3 pi bonds in this molecule
9. CS2 - linear sp
PCl3 - trigonal pyramidal sp3
COCl2 - trigonal plane sp2
SeF4 - tetragonal pyramidal sp3d
ICl4− - octahedral sp3d2
KrF2 - linear sp3d2
XeOF4 - tetragonal bipyramidal sp3d2
SO2 -bent plane sp2
OF2 - tetrahedral sp3
1.ionic,molecular,molecular,ionic
ОтветитьУдалить2.The chemical bonding that occurs in molecular compounds is a sharing of valence electrons called covalent bonding. Covalent bonds occur primarily between nonmetal atoms.
Ionic compounds are crystalline in nature, but with alternating cations and anions held together by attractive electrostatic forces called ionic bonds.
3.As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases.As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease. Eventually, a position is reached where the potential energy is at its lowest possible point. If the hydrogen atoms move any closer together, the repulsive force between the two positively charged nuclei (a third type of interaction) begins to dominate. When like charges are forced this close together, the resulting repulsive force is very strong, as can be seen by the sharp rise in energy at the far left of the diagram.
4.2,4,6
5.Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond.
It was once thought that the structure of a molecule, such as O3, consisted of one single bond and one double bond that shifted rapidly back and forth, as shown above. However, further studies showed that the two bonds are identical. Additionally, the properties of each bond are in between those expected for a single bond and a double bond between two oxygen atoms.
6.Beryllium is an alkaline earth metal, so you might expect it to form ionic bonds. However, due to its small size and relatively high ionization energy (compared to other metals), beryllium forms primarily molecular compounds when combined with many other elements. Since beryllium only has two valence electrons, it does not typically attain a full octet by sharing electrons.
Boron and aluminum, with three valence electrons, also tend to have an incomplete octet when they form covalent compounds.
There are a number of molecules whose total number of valence electrons is an odd number. It is not possible for all of the atoms in such a molecule to satisfy the octet rule. An example is nitrogen dioxide (NO2). Each oxygen atom contributes six valence electrons and the nitrogen atom contributes five, for a total of 17.
Starting with the third period, the d sublevel becomes available, so it is possible to use these orbitals in bonding, resulting in more than eight electrons around the central atom.
10.This bonds is considered a coordinate covalent bond, which is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.
Test 9.1
ОтветитьУдалить1) Ionic, molecular, molecular, ionic.
2) The chemical bonding that occurs in molecular compounds is a sharing of valence electrons called covalent bonding. Covalent bonds occur primarily between nonmetal atoms. Ionic compounds are crystalline in nature, but with alternating cations and anions held together by attractive electrostatic forces called ionic bonds.
3) As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases. As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease. Eventually, a position is reached where the potential energy is at its lowest possible point. If the hydrogen atoms move any closer together, the repulsive force between the two positively charged nuclei (a third type of interaction) begins to dominate. When like charges are forced this close together, the resulting repulsive force is very strong, as can be seen by the sharp rise in energy at the far left of the diagram.
4) 2,4,6
5) Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond. It was once thought that the structure of a molecule, such as O3, consisted of one single bond and one double bond that shifted rapidly back and forth, as shown above. However, further studies showed that the two bonds are identical. Additionally, the properties of each bond are in between those expected for a single bond and a double bond between two oxygen atoms.
6) Beryllium is an alkaline earth metal, so you might expect it to form ionic bonds. However, due to its small size and relatively high ionization energy (compared to other metals), beryllium forms primarily molecular compounds when combined with many other elements. Since beryllium only has two valence electrons, it does not typically attain a full octet by sharing electrons. Boron and aluminum, with three valence electrons, also tend to have an incomplete octet when they form covalent compounds. There are a number of molecules whose total number of valence electrons is an odd number. It is not possible for all of the atoms in such a molecule to satisfy the octet rule. An example is nitrogen dioxide (NO2).
10) This bonds is considered a coordinate covalent bond, which is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.
Test 9.2
ОтветитьУдалить1) The molecular geometry, or shape, of a molecule is an important factor that affects the physical and chemical properties of a compound. Those properties include melting and boiling points, solubility, density, and the types of chemical reactions that a compound undergoes.
2) Molecular geometry is the three-dimensional arrangement of atoms in a molecule. The total number of electron pairs, both bonding pairs and lone pairs, leads to what is called the electron domain geometry. Electron domain geometries are one of the five learned so far: linear, trigonal planar, tetrahedral, trigonal bipyramidal, or octahedral. However, when one or more of the bonding pairs of electrons is replaced with a lone pair, the molecular geometry, or actual shape of the molecule, is altered.
3) The valence shell is the outermost occupied shell of electrons in an atom. This shell holds the valence electrons, which are the electrons that are involved in bonding and shown in a Lewis structure. The valence-shell electron pair repulsion model, or VSEPR model, states that a molecule will adjust its shape so that the valence electron pairs stay as far apart from each other as possible. This makes sense, based on the fact that negatively charged electrons repel one another.
4) a. 5 b.4 c.6 d.2 e.3 f.4
5) As for methane and ammonia, the domain geometry for a molecule with four electron pairs is tetrahedral. In the water molecule, two of the electron pairs are lone pairs rather than bonding pairs. The molecular geometry of the water molecule is referred to as bent. The H-O-H bond angle is 104.5°, which is smaller than the bond angle in NH3.
6) The Lewis structure for SF4 contains four single bonds and a lone pair on the sulfur atom. Because of the greater repulsion of a lone pair, it is one of the equatorial atoms that is replaced by a lone pair. The geometry of the molecule is called a distorted tetrahedron or seesaw.
7) SF2 - bent
PBr3 - trigonal planar
AlCl3 - trigonal planar
TeCl4 - seesaw
HCN - linear
8) NO3− - trigonal planar
ICl2− - linear
ClO3− - trigonal pyramide
PO43− - tetrahedral
SeCl3− - trigonal bipyramide
9) The geometry of the BH3 molecule is called trigonal planar. The fluorine atoms are positioned at the vertices of an equilateral triangle. The H-B-H angle is 120°, and all four atoms lie in the same plane. The domain geometry for a molecule with four electron pairs is tetrahedral, as was seen with CH4. In the AsH3 molecule, one of the electron pairs is a lone pair rather than a bonding pair. The molecular geometry of NH3 is called trigonal pyramidal(107°).
10) Trigonal bipyramidal domain geometry, linear molecular geometry.
11) Octahedral domain geometry, fluorine atoms angles are equal to 90°.
Test 9.3
Удалить1) A bond with an electronegativity difference between 0.4 and 1.7 is called a polar covalent bond.
2) Diatomic molecules are molecules composed of two atoms of the same or different chemical elements.
3) An easy way to illustrate the uneven electron distribution in a polar covalent bond is to use the Greek letter, delta (δ) along with a positive or negative sign to indicate that an atom has a partial positive or negative charge. The atom with the greater electronegativity acquires a partial negative charge, while the atom with the lesser electronegativity acquires a partial positive charge. The delta symbol is used to indicate that the quantity of charge is less than one.
4) Carbon dioxide (CO2) is a linear molecule. The oxygen atoms are more electronegative than the carbon atom, so there are two individual dipoles pointing outward from the C atom to each O atom. However, since the dipoles are of equal strength and are oriented in this way, they cancel each other out, and the overall molecular polarity of CO2 is zero.
5) Van der Waals forces are the weakest intermolecular force and consist of dipole-dipole forces and dispersion forces. Dipole-dipole forces are the attractive forces that occur between polar molecules. Dispersion forces are also considered a type of van der Waals force and are the weakest of all intermolecular forces. They are often called London forces after Fritz London (1900-1954), who first proposed their existence in 1930. London dispersion forces are intermolecular forces that occur between all atoms and molecules due to the random motion of electrons. A hydrogen bond is an intermolecular attractive force in which a hydrogen atom, that is covalently bonded to a small, highly electronegative atom, is attracted to a lone pair of electrons on an atom in a neighboring molecule. Hydrogen bonds are very strong compared to other dipole-dipole interactions.
6) Hydrogen bonding occurs only in molecules where hydrogen is covalently bonded to one of three elements: fluorine, oxygen, or nitrogen. These three elements are so electronegative that they withdraw the majority of the electron density from the covalent bond with hydrogen, leaving the H atom very electron-deficient. Because the hydrogen atom does not have any electrons other than the ones in the covalent bond, its positively charged nucleus is almost completely exposed, allowing strong attractions to other nearby lone pairs.
7) The energy required to disrupt the intermolecular forces between molecules is far less than the energy required to break the ionic bonds in a crystalline ionic compound. Since molecular compounds are composed of neutral molecules, their electrical conductivity is generally quite poor, whether in the solid or liquid state. Ionic compounds do not conduct electricity well in the solid state because of their rigid structures, but they conduct well when they are molten (in the liquid state) or dissolved in water. The water solubility of molecular compounds is variable and depends primarily on the type of intermolecular forces involved. Substances that exhibit hydrogen bonding or dipole-dipole forces are generally water soluble, whereas those that exhibit only London dispersion forces are generally insoluble. Most, but not all, ionic compounds are quite soluble in water.
8) P-H, Br-C, Cl-F, Al-N, K-O
9) CBr4 — tetrahedral, nonpolar
H2S -- bent plane, polar
BF3 -- trigonal plane, nonpolar
PCl3 -- trigonal pyramidal, polar
SeF4 -- tetragonal pyramidal, polar
BeCl2 – linear, nonpolar
ClF3 -- trigonal bipyramidal, nonpolar
CH2Cl2 -- trigonal pyramidal, polar
SF6 -- tetragonal bipyramidal, nonpolar
10) In order for a substance to enter the gas phase, its particles must completely overcome the intermolecular forces holding them together. Therefore, a comparison of boiling points is essentially equivalent to comparing the strengths of the attractive intermolecular forces exhibited by the individual molecules. For small molecular compounds, London dispersion forces are the weakest intermolecular forces. Dipole-dipole forces are somewhat stronger, and hydrogen bonding is a particularly strong form of dipole-dipole interaction. However, when the mass of a nonpolar molecule is sufficiently large, its dispersion forces can be stronger than the dipole-dipole forces in a lighter polar molecule.
Удалитьa.Br2 b.HCl c.Ar d.CH4 e.PH3
11) The physical state and properties of a particular compound depend largely on the type of chemical bonding it displays. Molecular compounds, sometimes called covalent compounds, display a wide range of physical properties due to the different types of intermolecular attractions discussed in this lesson. The melting and boiling points of molecular compounds are generally quite low compared to those of ionic compounds. This is because the energy required to disrupt the intermolecular forces between molecules is far less than the energy required to break the ionic bonds in a crystalline ionic compound.
Test 9.4
Удалить1) Valence bond theory states that covalent bonds are formed by the overlap of partially filled atomic orbitals.
2) Hybridization is the mixing of the atomic orbitals in an atom to produce a set of hybrid orbitals. When hybridization occurs, it must do so as a result of the mixing of nonequivalent orbitals. For example, s and p orbitals can hybridize, but p orbitals cannot hybridize with other p orbitals. Hybrid orbitals are the atomic orbitals obtained when two or more nonequivalent orbitals from the same atom combine in preparation for bond formation. In the current case of carbon, the single 2s orbital hybridizes with the three 2p orbitals to form a set of four hybrid orbitals, called sp3 hybrids.
3) a.sp b.sp3 c.sp3d2 d.sp2 e.sp3d
4) An optimum distance between the two nuclei, equal to the bond length, is eventually attained, and the potential energy reaches a minimum. At this point, a stable single covalent bond has formed between the two hydrogen atoms. Other covalent bonds form in the same way as unpaired electrons from two atoms “match up” to form the bond. In a fluorine atom, there is an unpaired electron in one of the 2p orbitals. When a F2 molecule forms, the 2p orbitals from each of the two atoms overlap to produce the F−F covalent bond. The overlapping orbitals do not have to be of the same type.
5) a.120 b. different c.180 d.109,5
6) A sigma bond (σ bond) is a bond formed by the overlap of orbitals in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms. A pi bond (π bond) is a bond formed by the overlap of orbitals in a side-by-side fashion, with the electron density concentrated above and below the plane of the nuclei of the bonding atoms. Three sigma bonds are formed by each carbon atom with its hybrid orbitals. The pi bond is the “second” bond of the double bond between the carbon atoms and is shown as an elongated blue lobe that extends both above and below the plane of the molecule, which contains the six atoms and all of the sigma bonds.
7) a.sigma bond b.sp c.sigma-pi bond
8) There are 10 sigma bonds and 3 pi bonds in this molecule.
9) CS2 – linear, sp
PCl3 -- trigonal pyramidal, sp3
COCl2 -- trigonal plane, sp2
SeF4 -- tetragonal pyramidal, sp3d
ICl4− -- octahedral, sp3d2
KrF2 – linear, sp3d2
XeOF4 -- tetragonal bipyramidal, sp3d2
SO2 -- bent plane, sp2
OF2 – tetrahedral, sp3
Grammar test - 81%
Удалить
ОтветитьУдалить1. People find that tourism is harmful because , they fear some tourists are showing disrespect to the city and have introduced laws to clampdown on certain behaviour. For example, Romans don't like to see tourists walking around bare-chested, they don't like to see them wading in their fountains - so really the objective is to improve the life of the city for residents and for tourists themselves.
2. The most visited city last year was Bangkok, in Thailand. Now Bangkok is very popular among tourists because there are a lot of “amazing” skyscrapers ( I don’t like them). And almost every person has a dream to take photo of yourself in a pool which is located on a roof of a skyscraper.
1)Tourism is harmful because some tourists are showing disrespect to the other cities and countries. Visitors can misbehave and disturb local people.
ОтветитьУдалить2) Bangkok was the most visited city in 2018. I think that the reason is a big amount of interesting places. Thailand's culture is famous for its hospitality.
1)Which cities have decided to impose restrictions on tourism?
Удалить2)Why did they do it?
3)Why do people travel?
4)What problems does travelling cause?
5)Why do the authorities of Rome introduce new restrictions?
6)What Romans don't like about the tourists?
7)What does the word "objective" mean in this text?
8)What is the Disneyfication?
9)Which way visitors can not bringing much money into the city Bruges in Belgium?
10) Why do people don't like cruise visitors?
1. Tourism can be harmful because lots of people are visiting and locals and tourists have differing attitudes towards the way they respect these beautiful and historic sites.
ОтветитьУдалить2. I think Bangkok was the most visited city in 2018 according to Mastercard’s Global Destination Cities Index because there are lots of temples, places to see. Thailand's culture is very interesting and unique, the nature is wonderful and Bangkok is located not far away from the sea, that means, that in the morning you can lay on the beach and in the evening enjoy big city life. Thailand is also located next to China and its easy for Chinese to get there.
1. Why has traveling became easier?
2. What have Italian authorities introduced?
3. What is the main goal of the new law?
4. What does it mean "to clampdown"?
5. What Romans don't like in tourists?
6. Where Bruges is located?
7. What is the main problem in Bruges?
8. Why did Belgium authorities decided to cap a number of cruisers?
9. What does Disneyfication mean?
10. What is the message from the city authorities?
1 What problem do we face with because of tourism?
ОтветитьУдалить2 What theme are participants of the program discussing?
3 Where does the journey of the program starts?
4 What features don’t Romans like mostly in tourists?
5 Why can tourist receive fine in Rome?
6 Can you tell other word for “trying to stop or limit people doing something”
7 Where does Disneyfication happen?
8 What does the name “Disneyfication” mean?
9 What is the problem connected with cruises in Bruges?
10 Earlier I asked you what the most visited city in 2018 was? Was it…
a) London
b) New York, or
c) Bangkok?
Grammar test 81%
ОтветитьУдалитьReading, test 1
ОтветитьУдалить1. a) CaBr2 - ionic
b) PCl3 - molecular
c) H2S - molecular
d)ZnO - ionic
2. The difference here ionic and covalent bonds is a covalent bond is a bond in which two atoms share one or more pairs of electrons and an ionic compound is an electrically neutral compound consisting of positive and negative ions.
3. As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. For example, the single electrons possessed by each hydrogen atom begin to repel each other, causing the potential energy of the system to increase. However, attractive forces also begin to develop between each electron and the positively charged nucleus of the other atom, causing a decrease in potential energy. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases. Remember, a lower potential energy is indicative of a more stable system. As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease. Eventually, a position is reached where the potential energy is at its lowest possible point. If the hydrogen atoms move any closer together, the repulsive force between the two positively charged nuclei (a third type of interaction) begins to dominate. When like charges are forced this close together, the resulting repulsive force is very strong, as can be seen by the sharp rise in energy at the far left of the diagram.
4. Two atoms are shared between atoms in a single covalent bond. Four electrons are shared between atoms in a double covalent bond. Six electrons are shared between atoms in a single covalent bond.
5. Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond. It was once thought that the structure of a molecule, such as O3, consisted of one single bond and one double bond that shifted rapidly back and forth, as shown above. However, further studies showed that the two bonds are identical. Additionally, the properties of each bond are in between those expected for a single bond and a double bond between two oxygen atoms.
6. Beryllium is an alkaline earth metal, so you might expect it to form ionic bonds. However, due to its small size and relatively high ionization energy (compared to other metals), beryllium forms primarily molecular compounds when combined with many other elements. Since beryllium only has two valence electrons, it does not typically attain a full octet by sharing electrons. Boron and aluminum, with three valence electrons, also tend to have an incomplete octet when they form covalent compounds. There are a number of molecules whose total number of valence electrons is an odd number. It is not possible for all of the atoms in such a molecule to satisfy the octet rule. An example is nitrogen dioxide (NO2). Each oxygen atom contributes six valence electrons and the nitrogen atom contributes five, for a total of 17. Starting with the third period, the d sublevel becomes available, so it is possible to use these orbitals in bonding, resulting in more than eight electrons around the central atom.
10. This bonds is considered a coordinate covalent bond, which is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.
11. a, c, e
Grammar test 81%
ОтветитьУдалитьTest 9.1
ОтветитьУдалить1. ionic,molecular,molecular,ionic
2. The chemical bonding that occurs in molecular compounds is a sharing of valence electrons called covalent bonding. Covalent bonds occur primarily between nonmetal atoms.
3. As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases. As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease.
4. 2, 4, 6
5. Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond.
6. Beryllium is an alkaline earth metal, so you might expect it to form ionic bonds. However, due to its small size and relatively high ionization energy (compared to other metals), beryllium forms primarily molecular compounds when combined with many other elements. Since beryllium only has two valence electrons, it does not typically attain a full octet by sharing electrons.
Boron and aluminum, with three valence electrons, also tend to have an incomplete octet when they form covalent compounds.
10. This bonds is considered a coordinate covalent bond, which is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.
11. а, с, е
Test 9.2
ОтветитьУдалить1) The molecular geometry, or shape, of a molecule is an important factor that affects the physical and chemical properties of a compound. Those properties include melting and boiling points, solubility, density, and the types of chemical reactions that a compound undergoes.
2) Molecular geometry is the three-dimensional arrangement of atoms in a molecule. The total number of electron pairs, both bonding pairs and lone pairs, leads to what is called the electron domain geometry. Electron domain geometries are one of the five learned so far: linear, trigonal planar, tetrahedral, trigonal bipyramidal, or octahedral. However, when one or more of the bonding pairs of electrons is replaced with a lone pair, the molecular geometry, or actual shape of the molecule, is altered.
3) The valence shell is the outermost occupied shell of electrons in an atom. This shell holds the valence electrons, which are the electrons that are involved in bonding and shown in a Lewis structure. The valence-shell electron pair repulsion model, or VSEPR model, states that a molecule will adjust its shape so that the valence electron pairs stay as far apart from each other as possible. This makes sense, based on the fact that negatively charged electrons repel one another.
4) a. 5 b.4 c.6 d.2 e.3 f.4
5) As for methane and ammonia, the domain geometry for a molecule with four electron pairs is tetrahedral. In the water molecule, two of the electron pairs are lone pairs rather than bonding pairs. The molecular geometry of the water molecule is referred to as bent. The H-O-H bond angle is 104.5°, which is smaller than the bond angle in NH3.
6) The Lewis structure for SF4 contains four single bonds and a lone pair on the sulfur atom. Because of the greater repulsion of a lone pair, it is one of the equatorial atoms that is replaced by a lone pair. The geometry of the molecule is called a distorted tetrahedron or seesaw.
7) SF2 - bent
PBr3 - trigonal planar
AlCl3 - trigonal planar
TeCl4 - seesaw
HCN - linear
8) NO3− - trigonal planar
ICl2− - linear
ClO3− - trigonal pyramide
PO43− - tetrahedral
SeCl3− - trigonal bipyramide
9) The geometry of the BH3 molecule is called trigonal planar. The fluorine atoms are positioned at the vertices of an equilateral triangle. The H-B-H angle is 120°, and all four atoms lie in the same plane. The domain geometry for a molecule with four electron pairs is tetrahedral, as was seen with CH4. In the AsH3 molecule, one of the electron pairs is a lone pair rather than a bonding pair. The molecular geometry of NH3 is called trigonal pyramidal(107°).
10) Trigonal bipyramidal domain geometry, linear molecular geometry.
11) Octahedral domain geometry, fluorine atoms angles are equal to 90°.
Test 9.3
ОтветитьУдалить1. A bond in which the electronegativity difference between the atoms is between 0.4 and 1.7 is called a polar covalent bond.
2. Diatomic molecules are molecules composed of only two atoms, of the same or different chemical elements. For example N2 or HF.
3. An easy way to illustrate the uneven electron distribution in a polar covalent bond is to use the Greek letter, delta (δ) along with a positive or negative sign to indicate that an atom has a partial positive or negative charge. The delta symbol is used to indicate that the quantity of charge is less than one.
4. For molecules with more than two atoms, the molecular geometry must also be taken into account when determining if the molecule is polar or nonpolar. Carbon dioxide (CO2) is a linear molecule. The oxygen atoms are more electronegative than the carbon atom, so there are two individual dipoles pointing outward from the C atom to each O atom. However, since the dipoles are of equal strength and are oriented in this way, they cancel each other out, and the overall molecular polarity of CO2 is zero.
5. Van der Waals forces are the weakest intermolecular force and consist of dipole-dipole forces and dispersion forces. Dispersion forces are also considered a type of van der Waals force and are the weakest of all intermolecular forces. London dispersion forces are intermolecular forces that occur between all atoms and molecules due to the random motion of electrons. Dipole-dipole forces are the attractive forces that occur between polar molecules. A hydrogen bond is an intermolecular attractive force in which a hydrogen atom, that is covalently bonded to a small, highly electronegative atom, is attracted to a lone pair of electrons on an atom in a neighboring molecule. Hydrogen bonds are very strong compared to other dipole-dipole interactions.
6. Hydrogen bonding occurs only in molecules where hydrogen is covalently bonded to one of three elements: fluorine, oxygen, or nitrogen. These three elements are so electronegative that they withdraw the majority of the electron density from the covalent bond with hydrogen, leaving the H atom very electron-deficient. Because the hydrogen atom does not have any electrons other than the ones in the covalent bond, its positively charged nucleus is almost completely exposed, allowing strong attractions to other nearby lone pairs.
7. The energy required to disrupt the intermolecular forces between molecules is far less than the energy required to break the ionic bonds in a crystalline ionic compound. Since molecular compounds are composed of neutral molecules, their electrical conductivity is generally quite poor, whether in the solid or liquid state. Ionic compounds do not conduct electricity well in the solid state because of their rigid structures, but they conduct well when they are molten (in the liquid state) or dissolved in water. The water solubility of molecular compounds is variable and depends primarily on the type of intermolecular forces involved.
8. P-H (0,01), Br-C (0.41), Cl-F (0.82), Al-N (1.43), K−O (2.62).
9. a. tetrahedral, nonpolar
b. bent, nonpolar
c. trigonal planar, nonpolar
d. trigonal pyramid, polar
e. trigonal bipyramid, polar
f. linear, nonpolar
g. T-shaped, polar
h. tetrahedral, polar
i. octahedral, nonpolar
10. a. ICl b. HF c. Kr d. CF4 e. NH3
Therefore, a comparison of boiling points is essentially equivalent to comparing the strengths of the attractive intermolecular forces exhibited by the individual molecules.
11. Ethanol contains hydrogen atoms that are bound to a highly electronegative oxygen atom, making for very polar bonds. Hydrogen bonds are very strong compared to other dipole-dipole interactions. A comparison of boiling points is essentially equivalent to comparing the strengths of the attractive intermolecular forces exhibited by the individual molecules.
Test 9.4
ОтветитьУдалить1) Valence bond theory states that covalent bonds are formed by the overlap of partially filled atomic orbitals.
2) Hybridization is the mixing of the atomic orbitals in an atom to produce a set of hybrid orbitals. When hybridization occurs, it must do so as a result of the mixing of nonequivalent orbitals. For example, s and p orbitals can hybridize, but p orbitals cannot hybridize with other p orbitals. Hybrid orbitals are the atomic orbitals obtained when two or more nonequivalent orbitals from the same atom combine in preparation for bond formation. In the current case of carbon, the single 2s orbital hybridizes with the three 2p orbitals to form a set of four hybrid orbitals, called sp3 hybrids.
3) a.sp b.sp3 c.sp3d2 d.sp2 e.sp3d
4) An optimum distance between the two nuclei, equal to the bond length, is eventually attained, and the potential energy reaches a minimum. At this point, a stable single covalent bond has formed between the two hydrogen atoms. Other covalent bonds form in the same way as unpaired electrons from two atoms “match up” to form the bond. In a fluorine atom, there is an unpaired electron in one of the 2p orbitals. When a F2 molecule forms, the 2p orbitals from each of the two atoms overlap to produce the F−F covalent bond. The overlapping orbitals do not have to be of the same type.
5) a.120 b. different c.180 d.109,5
6) A sigma bond (σ bond) is a bond formed by the overlap of orbitals in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms. A pi bond (π bond) is a bond formed by the overlap of orbitals in a side-by-side fashion, with the electron density concentrated above and below the plane of the nuclei of the bonding atoms. Three sigma bonds are formed by each carbon atom with its hybrid orbitals. The pi bond is the “second” bond of the double bond between the carbon atoms and is shown as an elongated blue lobe that extends both above and below the plane of the molecule, which contains the six atoms and all of the sigma bonds.
7) a.sigma bond b.sp c.sigma-pi bond
8) There are 10 sigma bonds and 3 pi bonds in this molecule.
9) CS2 – linear, sp
PCl3 -- trigonal pyramidal, sp3
COCl2 -- trigonal plane, sp2
SeF4 -- tetragonal pyramidal, sp3d
ICl4− -- octahedral, sp3d2
KrF2 – linear, sp3d2
XeOF4 -- tetragonal bipyramidal, sp3d2
SO2 -- bent plane, sp2
OF2 – tetrahedral, sp3
Grammar test - 90%
ОтветитьУдалить1. ionic,molecular,molecular,ionic
2. The chemical bonding that occurs in molecular compounds is a sharing of valence electrons called covalent bonding. Covalent bonds occur primarily between nonmetal atoms.
3. As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases. As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease.
4. 2, 4, 6
5. Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond.
6. Beryllium is an alkaline earth metal, so you might expect it to form ionic bonds. However, due to its small size and relatively high ionization energy (compared to other metals), beryllium forms primarily molecular compounds when combined with many other elements. Since beryllium only has two valence electrons, it does not typically attain a full octet by sharing electrons.
Boron and aluminum, with three valence electrons, also tend to have an incomplete octet when they form covalent compounds.
10. This bonds is considered a coordinate covalent bond, which is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.
Test 2
ОтветитьУдалить1.The molecular geometry, or shape, of a molecule is an important factor that affects the physical and chemical properties of a compound.
2.The molecular geometries of molecules change when the central atom has one or more lone pairs of electrons. The total number of electron pairs, both bonding pairs and lone pairs, leads to what is called the electron domain geometry. Electron domain geometries are one of the five learned so far: linear, trigonal planar, tetrahedral, trigonal bipyramidal, or octahedral.
3.The valence shell is the outermost occupied shell of electrons in an atom. This shell holds the valence electrons, which are the electrons that are involved in bonding and shown in a Lewis structure.The valence-shell electron pair repulsion model, or VSEPR model, states that a molecule will adjust its shape so that the valence electron pairs stay as far apart from each other as possible. This makes sense, based on the fact that negatively charged electrons repel one another.
4.a.5
b.4
c.6
d.2
e.3
f.4
5.As for methane and ammonia, the domain geometry for a molecule with four electron pairs is tetrahedral. In the water molecule, two of the electron pairs are lone pairs rather than bonding pairs. The molecular geometry of the water molecule is referred to as bent. The H-O-H bond angle is 104.5°, which is smaller than the bond angle in NH3.
6.he Lewis structure for SF4 contains four single bonds and a lone pair on the sulfur atom.Because of the greater repulsion of a lone pair, it is one of the equatorial atoms that is replaced by a lone pair.
7.a.bent
b.trigonal planar
c.trigonal planar
d.seesaw
e.linear
8.a.trigonal planar.
b.linear
c.trigonal pyramide
d.tetrahedral
e.trigonal bipyramide
9. AsH3 molecule adopts a trigonal pyramidal geometry, it would be reasonably to guess that AsH3 has the same angle (~107°) as NH3 molecule which has the same structure and because As belongs to the same period that N. The angle will be a little bit bigger than in NH3 because arsenic atom has a bigger radius than a nitrogen atom that causes less repulsive forse between hydrogen atoms.
BH3 molecule adopts a trigonal pyramidal geometry, so it will has a typical 120° angle.
10.It will be stable with trigonal bipyramidal geometry and an angle of 180° between fluorine atoms.
11.It will be distorted tetragonal bipyramidal with angles of 90° between four fluorine atoms.
Test 3
ОтветитьУдалить1. A bond whith an electronegativity difference between 0.4 and 1.7 is called a polar covalent bond.
2. Diatomic molecules are molecules composed of two atoms of the same or different chemical elements.
3. The symbols δ+ and δ− in a structural formula of a molecule denotes an incomplete charge of an atom.
4. A molecule is called nonpolar if its complete charge equales to zero. It can contain polar covalent bonds, the only condition is an ideal molecular geometry (linear, trigonal, tetragonal, regular bipyramidal).
5. Van der Waals forces are the weakest intermolecular forces, Dipole-dipole forces are stronger and Hydrogen bond forces are the strongest intermolecular attractive forces.
6. For a molecule to undergo hydrogen bonding, it must have a hydrogen atom covalently bonded to an atom of fluorine, oxygen, or nitrogen.
7. Ionic compounds do not conduct electricity well in the solid state because of their rigid structures, but they conduct well when they are molten or dissolved in water, because they form movable charged particles in a liquid. Movable charged particles can conduct electricity.
8. Cl−F, P−H, Br−C, Al−N, K−O.
9. CBr4 — tetrahedral nonpolar
H2S -- bent plane polar
BF3 -- trigonal plane nonpolar
PCl3 -- trigonal pyramidal polar
SeF4 -- tetragonal pyramidal polar
BeCl2 -- linear nonpolar
ClF3 -- trigonal bipyramidal nonpolar
CH2Cl2 -- trigonal pyramidal polar
SF6 -- tetragonal bipyramidal nonpolar
10. ICl < Br2
HCl < HF
Kr > Ar
CF4 > CH4
NH3 < PH3
11. Ethanol molecules form hydrogen bonds because they have a hydrogen atom connected to the oxygen atom. Dimethyl molecules don't have OH- groupes, so they can't form hydrogen bonds.
Test 4
ОтветитьУдалить1. Valence bond theory states that covalent bonds are formed by the overlap of partially filled atomic orbitals.
2. Hybridization is the mixing of the atomic orbitals in an atom to produce a set of hybrid orbitals. When hybridization occurs, it must do so as a result of the mixing of nonequivalent orbitals. For example, s and p orbitals can hybridize, but p orbitals cannot hybridize with other p orbitals. Hybrid orbitals are the atomic orbitals obtained when two or more nonequivalent orbitals from the same atom combine in preparation for bond formation. In the current case of carbon, the single 2s orbital hybridizes with the three 2p orbitals to form a set of four hybrid orbitals, called sp3 hybrids.
3. a.sp b.sp3 c.sp3d2 d.sp2 e.sp3d
4. An optimum distance between the two nuclei, equal to the bond length, is eventually attained, and the potential energy reaches a minimum. At this point, a stable single covalent bond has formed between the two hydrogen atoms. Other covalent bonds form in the same way as unpaired electrons from two atoms “match up” to form the bond. In a fluorine atom, there is an unpaired electron in one of the 2p orbitals. When a F2 molecule forms, the 2p orbitals from each of the two atoms overlap to produce the F−F covalent bond. The overlapping orbitals do not have to be of the same type.
5. a.120 b. different c.180 d.109,5
6. A sigma bond (σ bond) is a bond formed by the overlap of orbitals in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms. A pi bond (π bond) is a bond formed by the overlap of orbitals in a side-by-side fashion, with the electron density concentrated above and below the plane of the nuclei of the bonding atoms. Three sigma bonds are formed by each carbon atom with its hybrid orbitals. The pi bond is the “second” bond of the double bond between the carbon atoms and is shown as an elongated blue lobe that extends both above and below the plane of the molecule, which contains the six atoms and all of the sigma bonds.
7. a.sigma bond b.sp c.sigma-pi bond
8. There are 10 sigma bonds and 3 pi bonds in this molecule.
9. CS2 – linear, sp
PCl3 -- trigonal pyramidal, sp3
COCl2 -- trigonal plane, sp2
SeF4 -- tetragonal pyramidal, sp3d
ICl4− -- octahedral, sp3d2
KrF2 – linear, sp3d2
XeOF4 -- tetragonal bipyramidal, sp3d2
SO2 -- bent plane, sp2
OF2 – tetrahedral, sp3
Reading Test 9.2
ОтветитьУдалить1. The molecular geometry, or shape, of a molecule is an important factor that affects the physical and chemical properties of a compound.
2. The molecular geometries of molecules change when the central atom has one or more lone pairs of electrons. The total number of electron pairs, both bonding pairs and lone pairs, leads to what is called the electron domain geometry. Electron domain geometries are one of the five learned so far: linear, trigonal planar, tetrahedral, trigonal bipyramidal, or octahedral. However, when one or more of the bonding pairs of electrons is replaced with a lone pair, the molecular geometry, or actual shape of the molecule, is altered.
3. The valence shell is the outermost occupied shell of electrons in an atom. This shell holds the valence electrons, which are the electrons that are involved in bonding and shown in a Lewis structure. The valence-shell electron pair repulsion model, or VSEPR model, states that a molecule will adjust its shape so that the valence electron pairs stay as far apart from each other as possible. This makes sense, based on the fact that negatively charged electrons repel one another.
4. a) 5 b) 4 c) 6 d) 2 e) 3 f) 4
5. As for ammonia, the domain geometry for a molecule with four electron pairs is tetrahedral. In the water molecule, two of the electron pairs are lone pairs rather than bonding pairs. The molecular geometry of the water molecule is referred to as bent. The H-O-H bond angle is 104.5°, which is smaller than the bond angle in NH3.
6. The Lewis structure for SF4 contains four single bonds and a lone pair on the sulfur atom. The sulfur atom has five electron groups around it, which corresponds to the trigonal bipyramidal domain geometry. Because of the greater repulsion of a lone pair, it is one of the equatorial atoms that is replaced by a lone pair. The geometry of the molecule is called a distorted tetrahedron or seesaw.
7. a) bent
b) trigonal planar
c) trigonal planar
d) seesaw
e) linear
8. a) trigonal planar
b) linear
c) trigonal pyramide
d) tetrahedral
e) trigonal bipyramide
9. The geometry of the BH3 molecule is called trigonal planar. The fluorine atoms are positioned at the vertices of an equilateral triangle. The H-B-H angle is 120°, and all four atoms lie in the same plane. As for arsine or ammonia, in the arsine molecule, one of the electron pairs is a lone pair rather than a bonding pair. The molecular geometry of AsH3 is called trigonal pyramidal. The H-As-H angle is approximately 107°.
10. It will be stable with trigonal bipyramidal domain geometry and an angle of 180° between fluorine atoms. The result is a linear molecular geometry.
11. The geometry of the XeOF4 molecule is octahedral domain geometry. Angles between fluorine atoms are equal to 90°.
Алимханова
ОтветитьУдалить1)I think tourism is harmful because some tourists are showing disrespect to the other cities and countries. Visitors can misbehave and disturb local people.
2) Bangkok was the most visited city in 2018. I think that the reason is a big amount of interesting places. Thailand's culture is famous for its hospitality.
1. Why has travelling became easier?
2. Why have Italian authorities introduced special laws for tourists?
3. What does it mean "to clampdown"?
4. What features don’t Romans like mostly in tourists?
5. Why can tourist receive fine in Rome?
6. What is the main problem in Bruges?
7. What does Disneyfication mean?
8. Which way visitors can not bringing much money into the Bruges?
9. Why do citizens don't like cruise visitors?
10. What does an objective mean?
Test 3
ОтветитьУдалить1)C
2)A
3)B
4)A
5)B
6)B
7)B
8)А
9)D
10)A
11)A
12)B
13.)D
14)D
15)B
16)D
17)C
18)A
19)A
20)B
B)
21)off
22)up
23)across
24)for
25)up
C)
26)with
27)of
28)of
29)by
30)of
D)
31)in spite of the fact that she’s rich , she isn’t happy
32) June doesn’t work as hard as terry
33) he needn’t have paid me
34) he had never seen a dolphin before
35) no other chess player is as good as Collin
E)
36) so strong
37) had forgotten
38) was hit on the
39) so as no to
40) al thought
F)
41)was
42) was laughter at
43) had been
44) had recently been advised
45) will tease
G)
46)Ted has had a new window put in by a carpenter
47) Tommy has his clothes washed for him by his mother
48) she may had her hair permed tomorrow
49)Lord Sutcliffe is having his shoes cleaned at the moment
50) James had his car repaired by the mechanic
H)
51)At this evening they arrived home early
52) look at that beautiful black Alsatian police dog
53) she bought an expensive new black silk dress
54) all night the dog barked noisily in the garden
55) I’d like a big medium rare steak please
56) he is almost never late for work
57) she is often time the last student to finish the test
58) I probably won’t see James until tomorrow
59) he nearly always runs all the way r to school
60) I think these are extremely difficult
I)
61 he is so apologized for being so angry the night before night
62) he denied telling them Toms secret
63) she complained that her husband was always forgetting their wedding anniversary and added that he never remembered her birthday either
64) he suggested having quiet night at home for a change
65₽ he agreed to help her with the housework as long as she did the walking up
Test after paragraph
ОтветитьУдалить1.a ionic
b molecular
c molecular
d ionic.
2. Covalent bond is a result of sharing valence electrons between two or more nonmetal atoms.
Ionic bound is a result of attraction between oppositely charged particles due to the electrostatic forces.
3.As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases.As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease. Eventually, a position is reached where the potential energy is at its lowest possible point. If the atoms move any closer together, the repulsive force between the two positively charged nuclei (a third type of interaction) begins to dominate. When like charges are forced this close together, the resulting repulsive force is very strong, as can be seen by the sharp rise in energy at the far left of the diagram.
4. In a single covalent bond 2 electrons are shared. In a double covalent bond 4 electrons are shared.In a single covalent bond 6 electrons are shared.
5.Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond. These two bonds are identical the properties of each bond are in between those expected for a single bond and a double bond between two oxygen atoms.
6 Beryllium, due to its small size and relatively high ionization energy (compared to other metals), forms primarily molecular compounds
Boron and aluminum, with three valence electrons.
There are a number of molecules whose total number of valence electrons is an odd number. It is not possible for all of the atoms in such a molecule to satisfy the octet rule. An example is nitrogen dioxide (NO2). Each oxygen atom contributes six valence electrons and the nitrogen atom contributes five, for a total of 17.
Starting with the third period, the d sublevel becomes available, so it is possible to use these orbitals in bonding, resulting in more than eight electrons around the central atom.
10. Carbon has 4 valence electrons, nitrogen and oxygen have 5 and 6 valence electrons respectively. When forming a covalent bond with a carbon atom nitrogen or oxygen carbon atom is unable to have an octet of electrons, so in order the molecule to be stable a nitrogen or an oxygen atom completely contributes one of its lone pairs to form an extra bond. But carbon atom has no lone pairs to contribute because all of its 4 valence electrons are involved in forming of the covalent bounds.
11. a, c, e.
Listening
ОтветитьУдалитьIn today’s society the development of tourism has become a highly topical issue. To many people tourism causes pollution. Nowadays, tourism is threatening many animal habitats and species all over the world.
Many ecologist associations argue that the development of mindless tourism must affect natural habitat. To them, there is no doubt that the arrive of hundreds of eager tourists every year has a direct impact to the nature, increasing the level of pollution and breaking the natural balance of the nature , polluting people’s traditional custom at the same time.
Needless to say that currently because of globalisation and people’s desire to visit new lands have caused that people want to travel to remote areas, for instance visit a remote town in Africa, in the blink of an eye.
However, some steps have been taken for the last ten years. Currently, tourists have the possibility to practise another kind of tourism, more respectful with the nature. Tourists have the opportunity to work in social projects with the local people. It is definitely another way to visit a place, less aggressive, far away of traditional image that everyone has in their heads: beaches full of people throwing rubbish and polluting natural areas.
Fortunately, currently, there are a lot of travel agencies that offer this new tourism compatible with a sustainable development.
Summarizing the said above. It is of the utmost importance that people should be aware of the necessity to protect the natural habitat. We should find a happy medium between the desire to know new places and the right of animals and plants to develop in their natural habitats without curious tourists who are bothering all the time. Thus, conservation and tourism do not have to be necessarily enemies. Perhaps people should think if we do not care our planet, eventually we will not have any outstanding beaches or picturesque people to meet
Мамонтова Мария
ОтветитьУдалитьТест 9.1
1.a ionic
b molecular
c molecular
d ionic.
2. Covalent bond is a result of sharing valence electrons between two or more nonmetal atoms.
Ionic bound is a result of attraction between oppositely charged particles due to the electrostatic forces.
3.As the atoms approach one another, their electron clouds gradually begin to overlap, giving rise to several new interactions. As the atoms first begin to interact, the attractive force is stronger than the repulsive force, so the potential energy of the system decreases.As the two hydrogen atoms move closer and closer together, the potential energy continues to decrease. Eventually, a position is reached where the potential energy is at its lowest possible point. If the atoms move any closer together, the repulsive force between the two positively charged nuclei (a third type of interaction) begins to dominate. When like charges are forced this close together, the resulting repulsive force is very strong, as can be seen by the sharp rise in energy at the far left of the diagram.
4. In a single covalent bond 2 electrons are shared. In a double covalent bond 4 electrons are shared.In a single covalent bond 6 electrons are shared.
5.Studies have shown that the two identical bonds in O3 are stronger and shorter than a typical O-O single bond but longer and weaker than an O-O double bond. These two bonds are identical the properties of each bond are in between those expected for a single bond and a double bond between two oxygen atoms.
6 Beryllium, due to its small size and relatively high ionization energy (compared to other metals), forms primarily molecular compounds
Boron and aluminum, with three valence electrons.
There are a number of molecules whose total number of valence electrons is an odd number. It is not possible for all of the atoms in such a molecule to satisfy the octet rule. An example is nitrogen dioxide (NO2). Each oxygen atom contributes six valence electrons and the nitrogen atom contributes five, for a total of 17.
Starting with the third period, the d sublevel becomes available, so it is possible to use these orbitals in bonding, resulting in more than eight electrons around the central atom.
10. Carbon has 4 valence electrons, nitrogen and oxygen have 5 and 6 valence electrons respectively. When forming a covalent bond with a carbon atom nitrogen or oxygen carbon atom is unable to have an octet of electrons, so in order the molecule to be stable a nitrogen or an oxygen atom completely contributes one of its lone pairs to form an extra bond. But carbon atom has no lone pairs to contribute because all of its 4 valence electrons are involved in forming of the covalent bounds.
11. a, c, e.
МАМОНТОВА МАРИЯ
УдалитьТест 9.3
1. A bond in which the electronegativity difference between the atoms is between 0.4 and 1.7 is called a polar covalent bond.
2. Diatomic molecules are molecules composed of only two atoms, of the same or different chemical elements. For example N2 or HF.
3. An easy way to illustrate the uneven electron distribution in a polar covalent bond is to use the Greek letter, delta (δ) along with a positive or negative sign to indicate that an atom has a partial positive or negative charge. The delta symbol is used to indicate that the quantity of charge is less than one.
4. For molecules with more than two atoms, the molecular geometry must also be taken into account when determining if the molecule is polar or nonpolar. Carbon dioxide (CO2) is a linear molecule. The oxygen atoms are more electronegative than the carbon atom, so there are two individual dipoles pointing outward from the C atom to each O atom. However, since the dipoles are of equal strength and are oriented in this way, they cancel each other out, and the overall molecular polarity of CO2 is zero.
5. Van der Waals forces are the weakest intermolecular force and consist of dipole-dipole forces and dispersion forces. Dispersion forces are also considered a type of van der Waals force and are the weakest of all intermolecular forces. London dispersion forces are intermolecular forces that occur between all atoms and molecules due to the random motion of electrons. Dipole-dipole forces are the attractive forces that occur between polar molecules. A hydrogen bond is an intermolecular attractive force in which a hydrogen atom, that is covalently bonded to a small, highly electronegative atom, is attracted to a lone pair of electrons on an atom in a neighboring molecule. Hydrogen bonds are very strong compared to other dipole-dipole interactions.
6. Hydrogen bonding occurs only in molecules where hydrogen is covalently bonded to one of three elements: fluorine, oxygen, or nitrogen. These three elements are so electronegative that they withdraw the majority of the electron density from the covalent bond with hydrogen, leaving the H atom very electron-deficient. Because the hydrogen atom does not have any electrons other than the ones in the covalent bond, its positively charged nucleus is almost completely exposed, allowing strong attractions to other nearby lone pairs.
7. The energy required to disrupt the intermolecular forces between molecules is far less than the energy required to break the ionic bonds in a crystalline ionic compound. Since molecular compounds are composed of neutral molecules, their electrical conductivity is generally quite poor, whether in the solid or liquid state. Ionic compounds do not conduct electricity well in the solid state because of their rigid structures, but they conduct well when they are molten (in the liquid state) or dissolved in water. The water solubility of molecular compounds is variable and depends primarily on the type of intermolecular forces involved.
8. P-H (0,01), Br-C (0.41), Cl-F (0.82), Al-N (1.43), K−O (2.62).
9. a. tetrahedral, nonpolar
b. bent, nonpolar
c. trigonal planar, nonpolar
d. trigonal pyramid, polar
e. trigonal bipyramid, polar
f. linear, nonpolar
g. T-shaped, polar
h. tetrahedral, polar
i. octahedral, nonpolar
10. a. ICl b. HF c. Kr d. CF4 e. NH3
Therefore, a comparison of boiling points is essentially equivalent to comparing the strengths of the attractive intermolecular forces exhibited by the individual molecules.
11. Ethanol contains hydrogen atoms that are bound to a highly electronegative oxygen atom, making for very polar bonds. Hydrogen bonds are very strong compared to other dipole-dipole interactions. A comparison of boiling points is essentially equivalent to comparing the strengths of the attractive intermolecular forces exhibited by the individual molecules.
МАМОНТОВ МАРИЯ
УдалитьТест 9.2
1. The molecular geometry, or shape, of a molecule is an important factor that affects the physical and chemical properties of a compound.
2. The molecular geometries of molecules change when the central atom has one or more lone pairs of electrons. The total number of electron pairs, both bonding pairs and lone pairs, leads to what is called the electron domain geometry. Electron domain geometries are one of the five learned so far: linear, trigonal planar, tetrahedral, trigonal bipyramidal, or octahedral. However, when one or more of the bonding pairs of electrons is replaced with a lone pair, the molecular geometry, or actual shape of the molecule, is altered.
3. The valence shell is the outermost occupied shell of electrons in an atom. This shell holds the valence electrons, which are the electrons that are involved in bonding and shown in a Lewis structure. The valence-shell electron pair repulsion model, or VSEPR model, states that a molecule will adjust its shape so that the valence electron pairs stay as far apart from each other as possible. This makes sense, based on the fact that negatively charged electrons repel one another.
4. a) 5 b) 4 c) 6 d) 2 e) 3 f) 4
5. As for ammonia, the domain geometry for a molecule with four electron pairs is tetrahedral. In the water molecule, two of the electron pairs are lone pairs rather than bonding pairs. The molecular geometry of the water molecule is referred to as bent. The H-O-H bond angle is 104.5°, which is smaller than the bond angle in NH3.
6. The Lewis structure for SF4 contains four single bonds and a lone pair on the sulfur atom. The sulfur atom has five electron groups around it, which corresponds to the trigonal bipyramidal domain geometry. Because of the greater repulsion of a lone pair, it is one of the equatorial atoms that is replaced by a lone pair. The geometry of the molecule is called a distorted tetrahedron or seesaw.
7. a) bent
b) trigonal planar
c) trigonal planar
d) seesaw
e) linear
8. a) trigonal planar
b) linear
c) trigonal pyramide
d) tetrahedral
e) trigonal bipyramide
9. The geometry of the BH3 molecule is called trigonal planar. The fluorine atoms are positioned at the vertices of an equilateral triangle. The H-B-H angle is 120°, and all four atoms lie in the same plane. As for arsine or ammonia, in the arsine molecule, one of the electron pairs is a lone pair rather than a bonding pair. The molecular geometry of AsH3 is called trigonal pyramidal. The H-As-H angle is approximately 107°.
10. It will be stable with trigonal bipyramidal domain geometry and an angle of 180° between fluorine atoms. The result is a linear molecular geometry.
11. The geometry of the XeOF4 molecule is octahedral domain geometry. Angles between fluorine atoms are equal to 90°.
МАМОНТОВА МАРИЯ
УдалитьТест 9.4
1) Valence bond theory states that covalent bonds are formed by the overlap of partially filled atomic orbitals.
2) Hybridization is the mixing of the atomic orbitals in an atom to produce a set of hybrid orbitals. When hybridization occurs, it must do so as a result of the mixing of nonequivalent orbitals. For example, s and p orbitals can hybridize, but p orbitals cannot hybridize with other p orbitals. Hybrid orbitals are the atomic orbitals obtained when two or more nonequivalent orbitals from the same atom combine in preparation for bond formation. In the current case of carbon, the single 2s orbital hybridizes with the three 2p orbitals to form a set of four hybrid orbitals, called sp3 hybrids.
3) a.sp b.sp3 c.sp3d2 d.sp2 e.sp3d
4) An optimum distance between the two nuclei, equal to the bond length, is eventually attained, and the potential energy reaches a minimum. At this point, a stable single covalent bond has formed between the two hydrogen atoms. Other covalent bonds form in the same way as unpaired electrons from two atoms “match up” to form the bond. In a fluorine atom, there is an unpaired electron in one of the 2p orbitals. When a F2 molecule forms, the 2p orbitals from each of the two atoms overlap to produce the F−F covalent bond. The overlapping orbitals do not have to be of the same type.
5) a.120 b. different c.180 d.109,5
6) A sigma bond (σ bond) is a bond formed by the overlap of orbitals in an end-to-end fashion, with the electron density concentrated between the nuclei of the bonding atoms. A pi bond (π bond) is a bond formed by the overlap of orbitals in a side-by-side fashion, with the electron density concentrated above and below the plane of the nuclei of the bonding atoms. Three sigma bonds are formed by each carbon atom with its hybrid orbitals. The pi bond is the “second” bond of the double bond between the carbon atoms and is shown as an elongated blue lobe that extends both above and below the plane of the molecule, which contains the six atoms and all of the sigma bonds.
7) a.sigma bond b.sp c.sigma-pi bond
8) There are 10 sigma bonds and 3 pi bonds in this molecule.
9) CS2 – linear, sp
PCl3 -- trigonal pyramidal, sp3
COCl2 -- trigonal plane, sp2
SeF4 -- tetragonal pyramidal, sp3d
ICl4− -- octahedral, sp3d2
KrF2 – linear, sp3d2
XeOF4 -- tetragonal bipyramidal, sp3d2
SO2 -- bent plane, sp2
OF2 – tetrahedral, sp3
МАМОНТОВА МАРИЯ
ОтветитьУдалитьGrammar test 77%
9.1
ОтветитьУдалить1.
a) ionic
b)molecular
c)molecular
d)ionic
2)
Ionic bond is a chemical bond between two dissimilar atoms in which one atom gives up an electron to another. It takes place been similar atoms (i.e. two non-metals).
Covalent bond is the bond between similar atoms, when they come together to share the electron, instead of an atom taking an electron from another.
3)A covalent bond is currently conceived as a dense electron cloud mainly concentrated between the two nuclei.
As a result, the repulsive forces between the two positive nuclei are essentially cancelled out and overwhelmed by the attractive forces between the positive nuclei and the negative electrons.
This puts the two molecules at an energy extremum ( minimum) which is what is what nature strives for. As such, the molecule is a stable structure that can be encountered naturally.
4) 2,4,6
5) O2 has 1 double bond. O3 has a single and a double bond. So, in ozone, you have resonance structures, and the average bond is 1.5. The bond order for O2 is 2 and the bond order for O3 is 1.5. So, bond length for O2 is longer than that in O3.
6) Beryllium is an alkaline earth metal, so you might expect it to form ionic bonds. However, due to its small size and relatively high ionization energy (compared to other metals), beryllium forms primarily molecular compounds when combined with many other elements. Since beryllium only has two valence electrons, it does not typically attain a full octet by sharing electrons. Boron and aluminum, with three valence electrons, also tend to have an incomplete octet when they form covalent compounds. There are a number of molecules whose total number of valence electrons is an odd number. It is not possible for all of the atoms in such a molecule to satisfy the octet rule. An example is nitrogen dioxide (NO2).
10) This bonds is considered a coordinate covalent bond, which is a covalent bond in which one of the atoms contributes both of the electrons in the shared pair.
9.2
Удалить1) It can help identify whether or not the molecule is polar as well as identify if there are any "ends" of the molecule which can be more easily involved in a reaction.
2) Electron domain geometry is an indicator of molecular geometry. Electron domain talks about where the different pairs of electrons on a molecule are going to be at any given moment. For example, CH4 will have a tetrahedral geometry, because it's a carbon bonded to four different hydrogens, so it's got 4 different electron domains. Molecular geometry comes into play when we start taking the hydrogens off. With all of the hydrogens, the CH4's molecular geometry will be tetrahedral. If you take one away, then the molecular geometry will be trigonal planar. If you take two away it'll be linear.
So all of that is kind of to say that electron-domain usually stays the same for a given atom, and molecular geometry depends on the bonds that the central atom makes with the other atoms in the molecule.
3) The valence-shell electron pair repulsion model, or VSEPR model, states that a molecule will adjust its shape so that the valence electron pairs stay as far apart from each other as possible. This makes sense, based on the fact that negatively charged electrons repel one another. We will systematically classify molecules according to the number of bonding pairs of electrons and the number of nonbonding or lone pairs around the central atom.
4)
a)5
b)4)
c)6
d)2
e)3
f)4
5) As for methane and ammonia, the domain geometry for a molecule with four electron pairs is tetrahedral. In the water molecule, two of the electron pairs are lone pairs rather than bonding pairs. The molecular geometry of the water molecule is referred to as bent. The H-O-H bond angle is 104.5°, which is smaller than the bond angle in NH3.
6) The Lewis structure for SF4 contains four single bonds and a lone pair on the sulfur atom. Because of the greater repulsion of a lone pair, it is one of the equatorial atoms that is replaced by a lone pair.
7)
a) SF2 - bent
b) PBr3 - trigonal pyramidal
c) AlCl3 - trigonal planar
d) TeCl4 - see-saw
e) HCN - linear
8)
a) NO3- planar trigonal
b) ICl2- linear
c) CLO3- trigonal pyramidal
d) PO43- tetrahedral
e) SeCL3- trigonal bipyramidal
9) The geometry of the BH3 molecule is called trigonal planar. The hydrogen atoms are positioned at the vertices of an equilateral triangle. The H-B-H angle is 120°, and all four atoms lie in the same plane. In the molecule, one of the electron pairs is a lone pair rather than a bonding pair. The molecular geometry of AsH3 is called trigonal pyramidal. The H-As-H angle is approximately 107°.
10) XeF2 molecule contains three lone pairs. It will be stable with trigonal bipyramidal geometry and an angle of 180° between fluorine atoms.
11) Geometry of the XeOF4 molecule will be distorted tetragonal bipyramidal with angles of 90° between four fluorine atoms.
9.3
Удалить1) A bond whith an electronegativity difference between 0.4 and 1.7 is called a polar covalent bond.
2) Any molecule composed of exactly two atoms is a diatomic molecule. Examples include H2, O2, HCL, Cl2, CuO, CaO, F2, Br2, HBr, NO, CO, MgO, etc.
3) The symbols δ+ and δ− in a structural formula of a molecule denotes an incomplete charge of an atom.
4) Sure, if the polarity of the bonds cancels because of geometry.
Example: CO2 is a nonpolar molecule. The C-O bonds are polar, but they are of the same magnitude and in opposite directions, so they cancel each other. O=C=O
5) Van der Waals forces are the weakest intermolecular forces, Dipole-dipole forces are stronger and Hydrogen bond forces are the strongest intermolecular attractive forces.
6) For a molecule to undergo hydrogen bonding, it must have a hydrogen atom covalently bonded to an atom of fluorine, oxygen, or nitrogen.
7) Molecular compounds are composed of neutral molecules, which are incapable of conducting a current.The ions in an ionic compound are charged particles and can conduct electricity as long as they are not held in place in a solid crystal.
8) P-H (0,01), Br-C (0.41), Cl-F (0.82), Al-N (1.43), K−O (2.62)
9)
a) CBr4 - tetrahedral, nonpolar
b) H2S - bent, nonpolar
c) BF3 - trigonal planar, nonpolar
d) PCl3 - trigonal pyramid, polar
e) SeF4 - trigonal bipyramid, polar
f) BeCl2 - linear, nonpolar
g) ClF3 - T-shaped, polar
h) CH2Cl2 - tetrahedral, polar
i) SF6 - octahedral, nonpolar
10)
a) ICl > Br2
b) HCl < HF
c) Kr > Ar
d) CF4 > CH4
e) NH3 > PH3
Therefore, a comparison of boiling points is essentially equivalent to comparing the strengths of the attractive intermolecular forces exhibited by the individual molecules.
11) Ethanol contains hydrogen atoms that are bound to a highly electronegative oxygen atom, making for very polar bonds. Hydrogen bonds are very strong compared to other dipole-dipole interactions. A comparison of boiling points is essentially equivalent to comparing the strengths of the attractive intermolecular forces exhibited by the individual molecules.