learn smart chapter 7

Match each ideal bond angle with the correct electron-domain geometry in each case. Instructions

90-octahedral120-trgonal planar109.5-tetrahedral180-linear90 and 120-trgonal bipyramidal

Select all the statements that correctly describe the arrangement of lone pairs in systems with 5 and 6 electron domains.

In a trigonal bipyramidal system lone pairs prefer to occupy equatorial positions.If there are two lone pairs in an octahedral system they will be located opposite each other.

Which of the marked positions would a single lone pair prefer to occupy? Select all that apply.

b c d

A 5-electron domain system (shown) has two different types of positions for electron domains. The three positions marked "1" form a trigonal plane about the central atom and are called _______ positions, while the two positions marked "2" are ______ positions.

equatorial axial

The Lewis structure for the AsF5 is shown. The approximate value of the bond angle marked "a" is equal to _____ while the approximate value of the bond angle marked "b" is equal to _____. (Remember that this species has a three-dimensional shape, as indicated by the wedged and dashed bonds.)

90o, 120o

Which of the following options correctly describe the structure shown? Select all that apply.

C2 will have a linear geometry. The bond angles around C2 are approximately equal to 180°. C1 will have a tetrahedral geometry.

Which of the following correctly describes the bond angle in a molecule of the general type ABx?

The angle between two adjacent A-B bonds

In an ABx molecule, the angle between two adjacent A-B bonds is called _________the angle. This angle is determined by the number ____________of domains or groups surrounding the central atom.

bond electrons

Match each molecular geometry correctly to the electron-domain arrangement described. Instructions

linear- 5 electron domains and 3 lone pair sseesaw- 5,1 square planar- 6,2 bent- 4,2 trigonal pyramidal- 4,1

Match each number of electron domains with the correct electron-domain geometry.

linear-2 domains trigonal planar- 3 tetrahedral-4 trigonal bipyramidal - 5

Select all the options that correctly describe the bond angles associated with each electron-domain geometry.

The trigonal bipyramidal system has two different bond angles. A species with 3 electron domains will exhibit an ideal bond angle of 120o. A bond angle of 180o is observed for a linear system.

Select all the lettered options that correspond to equatorial positions in the image shown.

bcd

Molecular geometry is specified for a central atom in a structure. A "central" atom is _____.

any atom that is bonded to two or more other atoms

he molecular shape of a species, which is the arrangement of the bonded atoms around the central atom, is determined not only by the number of _________electron domains that join the atoms, but by the number of ______ electron domains as well, since these electrons also occupy space.

bonding non bonding

Select all the statements that correctly describe the bonding and geometry in the polyatomic ion SeCl5-.

- There is one lone pair associated with the Se atom. - This species is square pyramidal. - There are six electron groups around the Se atom.

Select all the statements that correctly describe dipole-dipole attractions.

Dipole-dipole 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.

Match each molecular geometry correctly to the electron-domain arrangement described.

bent-3 electron domains and 1 lone pair T-shaped- 5,2 square pyramidal- 6,1 tetrahedral- 4,0 linear-2,0

The electron-domain geometry of a species is the arrangement of electron_______ around the central atom, whereas the molecular geometry is the arrangement of bonded_______ . Two species with the same electron-domain geometry may have different molecular geometries.

domains atoms

Molecular shapes can be classified using the general designation ABx. Match each symbol in this designation with its correct meaning.

A is the central atom B is the terminal atom x is the number of terminal atoms

Select all the statements that correctly explain why lone pairs prefer to occupy equatorial positions in a system with five electron domains.

A lone pair in an equatorial position has more space. There is less repulsion between electron domains in equatorial positions.

Which of the following statements correctly describe the VSEPR model? Select all that apply.

According to this model, the valence electrons around a central atom are located as far from each other as possible. The VSEPR model is used to predict the geometry of a covalently bonded species. A Lewis structure is necessary in order to apply the VSEPR model.

Select all the statements that correctly describe the five basic electron-domain geometries.

An octahedral geometry indicates that there are six electron domains. A system with three electron domains will have a trigonal planar electron-domain arrangement.

Which of the following options correctly describe the structure shown? Select all that apply.

C1 will have a tetrahedral geometry. C2 will have a linear geometry. The bond angles around C2 are approximately equal to 180°.

Select all the statements that correctly describe how to determine the molecular shape of a species using VSEPR.

If unshared electron pairs are present, the molecular geometry will differ from the electron-domain geometry. Use the molecular formula to draw the Lewis structure. The total number of shared and unshared electron pairs around the central atom gives the electron-domain geometry.

True or false: When using VSEPR theory to determine molecular shape, a triple bond counts as a single electron domain even though it consists of 3 shared electron pairs.

True

Which species has a net dipole moment (i.e., are polar overall)? Select all that apply.

CH2Cl2NBr3

n Which of the following statements correctly defines intermolecular forces?

Intermolecular forces are the weak forces of attraction found between the individual molecules of a molecular covalent substance.

Which position will a lone pair preferentially occupy in a trigonal bipyramidal geometry and why?

The equatorial position because it affords more separation from other domains for the greater repulsion of a lone pair.

Why is BeF2 a nonpolar molecule?

BeF2 is linear and therefore the individual bond dipoles cancel to give no net dipole.

Which statement correctly describes the basic principle of VSEPR theory?

Each group of valence electrons around a central atom is located as far from the others as possible.

Match each description of molecular shape to the correct implication for polarity.

Individual bond dipoles will cancelfor a species that has identical bonds and a symmetrical geometry. Individual bond dipoles will not cancelfor a species with an unsymmetrical geometry. A species will be nonpolar overallif individual bond dipoles cancel. A species will be polar overallif individual bond dipoles do not cancel.

Select all the statements that correctly explain why bond angles in molecules containing lone pairs or multiple bonds may be different than the VSEPR ideal.

Multiple bonds contain higher electron densities that repel more than single bonds. Multiple bonds repel more strongly than single bonds that results in compression in adjacent bond angles. Lone pairs exert greater repulsion that causes compression in adjacent bond angles.

Draw the Lewis structures for NH2-, NH3, and NH4+. How would you expect the H-N-H bond angle in each species to compare?

NH2- < NH3 < NH4+

What approximate value will be observed for the bond angle marked in the structure shown? (Note that Lewis structures commonly do not reflect the actual shape of the species.)

Nitrogen will have a trigonal pyramidal molecular geometry. Carbon will have a trigonal planar molecular geometry.

Because lone pairs exert greater repulsions than bonded pairs, lone-pair domains always occupy the _____ positions in a trigonal bipyramid.

equatorial

Which of the following statements correctly describe how to determine whether a given molecule is polar or nonpolar? Select all that apply.

- for a molecule that has polar bonds, the geometry must be known in order to predict the overall polarity .- if a molecule contains no dipole moments across any bonds it will be non polar. - if the individual bond dipoles do not cancel, the molecule is polar.

The Lewis structure for one of the resonance forms of the sulfate ion, SO42-, is shown. What is the approximate value of the marked O-S-O bond angle?

109.5o

In the molecule KrBr2 there are _______electron domains surrounding the central Kr atom; _______bonding pair(s) and lone pair(s). The molecular geometry around the central atom is therefore ______.

5,2,3,linear

The boiling point of a molecular substance reflects the strength of its -------forces, the ------- forces between the individual molecules. The stronger these forces, the the amount of energy needed to separate the molecules, and the --------the boiling point will be.

intermolecular Blank 2: greater, more, higher, or larger Blank 3: higher or greater

In general, a lone pair repels bonding electron pairs _____ than bonding pairs repel each other. A lone pair will therefore _____ the bond angle between bonding pairs. A double bond has a similar effect.

more, decrease

Molecular shape is determined by the number of electron domains around a central atom, where an electron domain may be a(n) _____electron pair or any ______between two atoms.

nonbonded, bond