Chem Ch. 12
Which of the following options correctly reflect the relationship between dispersion forces and particle size? Select all that apply. Multiple select question. - Dispersion forces are strongest for small particles since they can get closer together in space. - Larger particles are more polarizable and experience stronger dispersion forces. - For molecules of similar shape, dispersion forces tend to increase with increasing molar mass. - Dispersion forces tend to decrease with size as larger particles are farther apart and therefore attract each other less.
- Larger particles are more polarizable and experience stronger dispersion forces. - For molecules of similar shape, dispersion forces tend to increase with increasing molar mass.
Which statement correctly explains how polarizability affects intermolecular forces? Multiple choice question. - A more polarizable molecule has a larger permanent dipole moment and experiences stronger dipole-dipole forces. - A more polarizable molecule has greater fluctuations in its dispersion forces and therefore experiences weaker intermolecular forces overall. - A more polarizable molecule experiences stronger dispersion forces and therefore stronger intermolecular forces overall. - A more polarizable molecule is more likely to experience hydrogen bonding, causing stronger intermolecular forces overall.
A more polarizable molecule experiences stronger dispersion forces and therefore stronger intermolecular forces overall.
Which of the following statements correctly describe dispersion or London forces? Select all that apply. Multiple select question. - Dispersion forces are stronger for smaller molecules. - All covalent compounds exhibit dispersion forces. - Dispersion forces are a weak attraction between temporary dipoles. - Dispersion forces are the primary intermolecular force exhibited by polar molecules.
All covalent compounds exhibit dispersion forces., Dispersion forces are a weak attraction between temporary dipoles.
Choice, Do not have well-defined shapes because they lack order in the arrangement of their particles Do not have well-defined shapes because they lack order in the arrangement of their particles
Amorphous solids
Which of the following statements correctly describe bonding and intermolecular forces? Select all that apply. Multiple select question. - Bonding forces are generally much stronger than intermolecular forces. Intermolecular forces involve partial or small charges that are far apart and are relatively weak. - For a molecular substance, the strength of the intermolecular forces determines the physical properties of its phases. - Bonding forces occur within the nucleus of the atom and are therefore strong. - Covalent bonds are a type of intermolecular force since they are found in molecules.
Bonding forces are generally much stronger than intermolecular forces, Intermolecular forces involve partial or small charges that are far apart and are relatively weak, For a molecular substance, the strength of the intermolecular forces determines the physical properties of its phases.
Choice, Have well-defined shapes because their particles are arranged in an orderly repeating pattern Have well-defined shapes because their particles are arranged in an orderly repeating pattern
Crystalline solids
Which of the following statements correctly describe dipole-dipole forces? Select all that apply. Multiple select question. - Any molecule that contains polar covalent bonds will exhibit dipole-dipole forces. - Dipole-dipole forces arise from the attraction between the like poles on two adjacent molecules. - Dipole-dipole forces are the forces of attraction between two polar molecules. - For two compounds of similar molar mass, the greater the molecular dipole moment, the stronger the dipole-dipole forces.
Dipole-dipole forces are the forces of attraction between two polar molecules, For two compounds of similar molar mass, the greater the molecular dipole moment, the stronger the dipole-dipole forces.
True or false: Dispersion forces are exhibited only by nonpolar molecules.
False
True or false: A bond between O and H within any molecule is called a hydrogen bond.
False A hydrogen bond is an intermolecular attraction between a hydrogen atom and a lone pair of electrons on an O, N, or F atom in another molecule or a different part of the same molecule. A hydrogen bond cannot exist between two atoms that are already covalently bonded to each other. To participate in hydrogen bonding a hydrogen atom must be covalently bonded to N, O, or F.
covalent radius
Half the distance between the nuclei of two covalently bonded atoms
van der Waals radius
Half the distance between the nuclei of two identical nonbonded atoms
Refer to the boiling point graph shown. H2O, NH3, and HF have much higher boiling points than the hydrides formed by other elements in the same group. These compounds experience ______ bonds between their molecules. Since this type of intermolecular force is very ______, it takes more ______ to separate the molecules so they can move from the liquid to the gas phase.
Hydrogen, strong, energy
Which of the following statements correctly describe the different packing arrangements observed for cubic unit cells? Select all that apply.
In hexagonal closest packing, the particles of the third layer lie directly over the particles of the first layer, The cubic close-packed structure has the repeating pattern abcabc, Cubic closest packing is based on the face-centered cubic cell.
______ involve the attraction between an charged particle and a nearby polar molecule. The most common example of such an intermolecular force of attraction is the dissolution of an ionic compound by water.
Ion-dipole forces
Hard and brittle with high melting points, and good thermal and electrical conductivity in the molten phase
Ionic
Fairly soft points and poor conductors of heat and electricity Fairly soft with low melting points and poor conductors of heat and electricity
Molecular
Which option correctly reflects the relationship between molecular shape and the strength of dispersion forces? Multiple choice question. - Molecules with a small surface area can pack more closely together and therefore experience stronger dispersion forces. - Two molecules of the same molar mass will experience the same dispersion forces regardless of their shape. - Molecules with a large surface area have more points of contact and therefore experience stronger dispersion forces.
Molecules with a large surface area have more points of contact and therefore experience stronger dispersion forces.
Very hard with high melting points but usually poor thermal and electrical conductors
Network covalent
When hydrogen is covalently bonded to ______, oxygen, or fluorine there will be an attraction between such a hydrogen and a(n) ______ pair of electrons on a nitrogen, oxygen, or fluorine atom on an adjacent molecule. This attraction is called a(n) bond, and it is the strongest type of intermolecular force between neutral species.
Nitrogen, lone, hydrogen
Dispersion forces are the only type of intermolecular force exhibited by atoms and by ______ molecules. Without the existence of dispersion forces, such substances could not exist in the ______ states of matter.
Nonpolar, condensed/ non-gaseous
Which of the following structural features would allow a molecular substance to exhibit hydrogen bonding between its molecules? Select all that apply. Multiple select question. - One or more hydrogen atoms - One or more O-H bonds - One or more oxygen atoms - One or more N-H bonds
One or more O-H bonds, One or more N-H bonds
The term _____ is used to describe how well the electron cloud around an atom responds to changes in its electronic environment.
Polarizability
As the boiling point graph shows, H2O, NH3, and HF deviate from the boiling point trend shown for the hydrides of the carbon group. Select the statement that correctly explains this deviation. Multiple choice question. - CH4 is much smaller than these compounds, and boiling point increases with size. - These compounds are ionic, and are therefore held together by much stronger attractive forces than those found between CH4 molecules. - The H bonding between molecules of H2O, NH3, and HF is much stronger than the intermolecular forces between CH4 molecules.
The H bonding between molecules of H2O, NH3, and HF is much stronger than the intermolecular forces between CH4 molecules.
Which of the following statements correctly describe the three types of cubic unit cells? Select all that apply. Multiple select question. - The body-centered cubic unit cell has 2 atoms per unit cell. - The coordination number for a face-centered cubic cell is 8. - The simple cubic unit cell has 6 atoms per unit cell. - Each particle in a simple cubic unit cell has a coordination number of 6. - The face-centered cubic cell has no particles in the center of the cube.
The body-centered cubic unit cell has 2 atoms per unit cell, Each particle in a simple cubic unit cell has a coordination number of 6, The face-centered cubic cell has no particles in the center of the cube.
bond length
The distance between the nuclei of two bonded atoms
In cubic closest packing
The particles of the third layer do not lie directly over the particles of the first layer. the particles of the third layer do not lie directly over the particles of the first layer.
In hexagonal closest packing
The particles of the third layer lie directly over the particles of the first layer. the particles of the third layer lie directly over the particles of the first layer.
van der Waals distance
The shortest distance between two non-bonded atoms in adjacent molecules
Which of the following options correctly defines polarizability? Multiple choice question. - This is a measure of how well an atom participates in a polar covalent bond. - This is a measure of how strongly an atom attracts the shared electron pair in a covalent bond. - This is a measure of the polarity of a covalent bond. - This is a measure of how the electron cloud around an atom responds to its electronic environment.
This is a measure of how the electron cloud around an atom responds to its electronic environment.
True or false: A compound containing one or more oxygen atoms is not necessarily capable of forming hydrogen bonds between its molecules.
True Reason: Correct. The presence of oxygen alone is not sufficient to allow a compound to form hydrogen bonds between its molecules. In addition to oxygen, the compound must have a hydrogen atom capable of hydrogen bonding, i.e., a hydrogen atom covalently bonded to N, O, or F.
The hexagonal close-packed structure has the pattern
ababab.
The cubic close-packed structure has the pattern
abcabc.
Molecular orbital (MO) theory proposes that metals bond through the formation of extremely large numbers of MOs whose energies are so close that they form a "band" of MOs. The lower energy MOs form the valence band and are occupied by valence electrons. In metallic solids, the empty ______ lies ______ above the valence band at higher energy. - conductor band; across a small energy gap - insulator band; directly - conduction band; directly - insulator band; across a small energy gap
conduction band; directly
The number of nearest neighbors for a particle (atoms or ions) in the unit cell of a crystal is called the _____ number of the particle.
coordination
Half the distance between the nuclei of two covalently bonded atoms is the ______, whereas half the shortest distance between the nuclei of identical nonbonded atoms is the ______.
covalent radius; van der Waals radius
Bonding forces include ionic bonds, metallic bonds, and ______ bonds. These types of forces are much ______ than the forces of attraction between individual molecules, which are called ______forces.
covalent, stronger or greater, intermolecular/ nonbonding/ non-bonding
According to MO band theory, metals bond by forming a large number of ______ MOs whose energies are so close that they form a continuous band. The lower energy MOs, occupied by the valence electrons, form the ______band, whereas the empty higher energy MOs form the ______ band.
delocalized/ shared, valence, conduction
The attraction between an ion and a nearby polar molecule is called an ion - ______ interaction. This attractive force is important when a(n) ______ compound dissolves in a polar solvent such as H2O.
dipole, ionic
All particles experience forces, a weak attraction that results from induced electron cloud distortion. These forces increase the overall attraction between particles. The more polarizable a particle is, the this effect will be.
dispersion, greater
The larger a molecule or atom, the _____ the number of electrons and the _____ polarizable it will generally be. The strength of the dispersion forces for a particular substance therefore generally _____ as molar mass increases, providing molecules of similar shape are compared.
greater; more; increases
Refer to the boiling point graph shown. H2O, NH3, and HF have much higher boiling points than the hydrides formed by other elements in the same group. These compounds experience ______ bonds between their molecules. Since this type of intermolecular force is very ______, it takes more ______ to separate the molecules so they can move from the liquid to the gas phase.
hydrogen or H, strong or powerful, energy/kinetic energy/heat
A momentary change in the electron density surrounding an atom or a molecule causes it to have a(n) _______ dipole even if it is not normally polar. This induces a similar effect in a nearby molecule or atom, and there will be a weak attraction between the two particles as a result. These weak interactions are called ______ forces or London forces.
instantaneous, dispersion
The particles in a crystal are arranged in an orderly 3-D array called the crystal ______. The simplest repeating unit of the crystal is called the unit ______.
lattice, cell
Soft to hard, varying melting points, and excellent conductors of electricity and heat as well as malleable and ductile
metallic
Molecules with a larger surface area have _____ points of contact between them than molecules with less surface area. This leads to _____ dispersion forces overall.
more; stronger
When two polar molecules are close to each other they will orient themselves so that the positive pole of one molecule attracts the ______ pole on the adjacent molecule. These intermolecular forces are called ______- ______forces.
negative or -, dipole, dipole
Amorphous solids often form from the rapid cooling of molten crystalline solids because ______. - recrystallization cannot occur quickly enough - the amorphous form will have a higher melting point than the crystalline form, in general - pockets of liquid remain inside the solid
recrystallization cannot occur quickly enough