CHapter 11

The structure shown contains _____ sigma bonds and ____ pi bonds

-6 2

Match each type of orbital with the corresponding electron-group arrangement sp sp2 sp3 sp3d sp3d2

1. linear 2. trigonal planar 3.tetrahydral 4.trigonal bipyramidal 5.octahedral

According to valence bond theaory, a(n) ________ bond is formed by the overlap of orbitals from two atoms. In order to explain the observed bond angles in many species it is a proposed that the atomic orbitals first form _____ orbitals, which differ from the orbitals of the isolated atoms.

Covalent hybrid

Place the following molecular orbitals in order of decreasing energy for species of B2, C2, and N2. start with the highest energy orbital.

σ₂p* π₂p* σ₂p π₂p

The valence molecular orbital diagram for Li2- is shown. THe molecular orbital bond order for this species is equal to _____ and Li2- is _____ stable than Li2

-1/2 -less

A central atom can be surrounded by five or six electron groups if _____ orbitals are available for bonding. The appropriate number of equivalent bonding orbitals is formed by combining _____ s orbital(s), ____ p orbital(s), and one or two _____ orbitals.

-d -one -three -d

Match each term with the appropriate electron arrangement paramagnetic diamagnetic

A molecular species with one or more unpaired electrons in an MO is _____ and will be attracted to a magnetic field, whereas a species with no unpaired electrons in its MO is ______ and will be slightly repelled by a magnetic field.

which partial orbital diagram correctly shows the hybrid orbitals and electron distribution of the N atom in the molecule NBr3

C sp3

Molecular orbitals formed from the combination of atomic s orbitals are called _______ molecular orbitals because they are cylindrically symmetrical. The molecular orbitals formed from atomic 1s orbitals are designated sigma*1s for the ______ molecular orbitals and sigma 1s for the _____ molecular orbital

sigma antibonding bonding

Valence bond theory describes covalent bonding as the localized overlap of half-filled valence-shell ________ atomic orbitals. Molecular orbital theory, on the other hand, escribes a molecule as a collection of nuclei with orbitals _____ over the whole molecule

hybrid delocalized

according to the molecular orbital model of covalent bonding, orbitals are viewed as ______ functions. the formation of a bond involves the mathematical combination of these functions, either by ______ to give an area of increased electron density, or by _____ to give an area of decreased electron density.

wave addition subtraction

According to molecular orbital (MO) theory, the twelve outermost electrons in the O2 molecule are distributed as follows:

8 bonding, 4antibonding

A group of sp3 hybrid orbitals is formed by the hybridization of ______s and _____p orbitals from the valence shell of an atom. These hybrid orbitals have the same ______ and energy.

one three shape

Select the statement that correctly describes the hybridization of phosphorus in PF5.

Phosphorus is sp3d hybridized.

Specify which hybrid orbitals are used by carbon atoms in the following species: CO CO2 CN-

Sp Sp sp

A particular hybrid orbital is designated sp3d2. what information is provided by the superscripts in this designation?

The number of each type of atomic orbital combined to produce this type of hybrid orbital.

In a polar covalent bond, the bonding MOs will be closer in energy to the AOs of the _______ electronegative atom

-more

Valence bond theory predicts that bromine will use _____ hybrid orbitals in BrF5.

sp3d2

Which of the following statements correctly describe a covalent bond in terms of valence bond theory?

* The greater the overlapped area the stronger the bond *The electrons of a shared pair must have opposite spins *a covalent bond is formed by the overlap of an orbital from each of the bonding atoms

which of the following statements correctly describe sp3 hybrid orbitals?

- An sp^3 orbital is unsymmetrical in shape, having one small and one large lobe. - The four sp^3 hybrid orbitals of a group are equivalent in shape and energy.

The valence molecular orbital diagram for the anion B2- is given.

- B2- has a shorter bond than B2 -The molecular orbital bond order is equal to 3/2. -B2- is paramagnetic

Which of the following options correctly describe the C=N double bond in the structure shown?

- the sigma bond is formed by the end to end overlap of an sp2 orbital from each atom -the pi bond of the C=n bond is formed by sideways overlap of a p orbital from each atom

Consider the reaction BF3 + NH3 → F3B―NH3 What changes in hybridization (if any) of the B atom are a result of this reaction? What changes in hybridization (if any) of the N atom are a result of this reaction?

-Before the reaction boron is sp2 hybridized, and after the reaction it is sp3 hybridized. -Before the reaction nitrogen is sp3 hybridized, and after the reaction it is sp3 hybridized.

correctly describe sigma and pi molecular orbitals

-Both atomic s and p orbitals can form sigma molecular orbitals -atomic p orbitals can combine to form either sigma or pi molecular orbitals -a pi bonding molecular orbital has two regions of high electron density

Why do the energies of the molecular orbitals formed for species of O2, F2, and Ne2 differ from those of the molecular orbitals for other period 2 elements?

-There is a large energy difference between 2s and 2p orbitals of O, F, and Ne; therefore, no s-p mixing occurs when molecular orbitals are formed

A molecular orbital is a region of space in a covalent species where electrons are likely to be found. The combination of two atomic orbitals always forms two molecular orbitals; the bonding molecular orbital, which is ______ in energy, and the antibonding molecular orbital, which is _______ in energy than the original atomic orbitals.

-lower -higher

a bond formed by sideways overlap of two p orbitals (one from each bonding atom) is alled a ____ bond. This type of bond has _____ regions of electron density.

-pi -2

The hybridization of one s and one p orbital will result in the formation of two __________ hybrid orbitals. This will leave _____ unhybridized valence p orbitals. lying at right angles to the hybrid orbitals

-sp -two

The combination of one s and two p orbitals will forma group of three ______ hybrid orbitals. THese hybrid orbitals adopt a(n) _______ planar geometry, and are at an angle of ______ to the remaining unhybridized p orbital

-sp2 -trigonal -120

arrange the steps for determining the hybridization of an atom in the correct order.

1) Draw a Lewis structure using the molecular formula. 2) Count the number of electron groups surrounding the central atom 3) The number of bonding orbitals required is equal to the number of electron groups 4) Build the appropriate combination of atomic orbitals based on the number of bonding orbitals required.

correct equation for calculatin molecular orbital bond order?

1/2 [(# of e- in bonding MO) - (# of e- in antibonding MO)]

Predict the geometry of sulfur dichloride (SCl2) and the hybridization of the sulfur atom.

Bent SP3

Select the arrangement which shows the species in order of increasing stability: Li2, Li2+, Li2−.

Li2− = Li2+ < Li2

When should the VSEPR model and hybridization theory be applied to describe bonding?

Whenever an observed molecular shape needs to be rationalized in terms of atomic orbitals.

Molecular orbitals can be formed by the combination of multiple atomic orbitals, allowing eectrons to be ______ or shared between several atoms. The molecular orbital model therefore allows a better descritotion of the bonding in _______ structures than VB theory, which depicts electrons as being ______ between two atoms at a time

delocalized resonance localized

a double bond is _______ a single bond because the strength of the pi bond component is ____ that of the sigma bond ocmponent

less than twice as strong as -weaker than

valence bond theory describes a single covalent bond as the ______ of orbitals form two atoms to form a shared space, which is occupied by ______ electrons

overlap 2

According to valence bond theory, which orbitals on N and H overlap in the NH3 molecule?

sp3 on N overlaps with 1s on H

The valence molecular orbital diagram for the cation f2+ is shown. which of the following options correctly interpret this diagram?

* F2+ has a stronger bond than F2 *The olecular orbital bond order is equal to 3/2

The valence molecular orbital diagram for Be2+ is shown, which of the following statements correctly interpret the diagram?

*Be2+ is more likley to exist than Be2 -be2+ has a weaker bond than H2 -Mo bond order for Be2+ is 1/2

which of the following statements correctly Describe hybrid orbitals

*The spatial orientations of the hybrid orbitals match observed molecular shapes *the shape and orientation of a hybrid orbital allow maximum overlap with an orbital from another atom to form a bond *the type of hybrid orbital formed varies depending on the specific combination of atomic orbitals

The lewis structure for the molecule NF3 is shown. Which of the following statements correctly describe the bonding in this molecule?

- Bond angles for this molecule are slightly less than 109.5 - The N uses one sp³ hybrid orbital to form each N-F bond

Which of the following steps are necessary to determine the hybridization of the central atom?

- Draw the Lewis structure of the molecule - Deduce the hybridization of the central atom based on the geometry of the molecule - Predict the geometry of the molecule using the VESPR model

correctly describe an MO energy-level diagram

- The MO diagram typically includes valence-shell molecular orbitals only. - The MO diagram can be used to calculate bond order and predict the stability of a species. - The MO diagram shows the relative energy and number of electron in each MO.

why is the hybridization model necessary to explain the bonding in a molecule such as CH4?

- The atomic electron configuration of carbon cannot account for four equivalent bonds. - The observed bond angles cannot be explained with reference to atomic orbitals.

The MO diagram for the hydroxide ion -OH is shown.

-The MO bond order is given by 2/2=1 -there are 3 nonbonding MO's in this species -the -OH is a fairly stable species

Atomic orbitals that are not involved in bonding are called ______ MOs. THese MOs will have _____ energy as to the isolated orbitals

-nonbonding -the same

A carbon-carbon triple bond in a molecule may give rise to the existence of cis and trans isomers.

False

Which of the following statements correctly defines hybrid orbitals

Orbitals used for bonding that are formed by "mixing" atomic orbitals from the same atom

Sigma Bonds vs. Pi Bonds

Sigma bond allows free rotation about the bond axis. Pi bonds restrict rotation about the bond axis

Carbon uses ______ hybrid orbitals in ClCN.

sp