Chapter 9: Molecular Geometry and Bonding Theories

According to molecular orbital theory, predict the bond order for H2 -. 2 1.5 2.5 0.5 1

0.5

How many unpaired electrons are in O2-, the superoxide anion? 2 3 0 1 4

1

The central iodine atom in IF5 has __________ unbonded electron pairs and __________ bonded electron pairs in its valence shell. 0, 5 5, 1 1, 4 4, 1 1, 5

1, 5

The O-C-O bond angle in the CO32- ion is approximately __________. 180° 90° 109.5° 120° 60°

120°

Assuming a molecular orbital diagram similar to that of O2, how many unpaired electrons are present in N2+? 2 3 4 0 1

1According to molecular orbital theory, predict the bond order for H2-. 2 1.5 2.5 Correct! 0.5 1

According to molecular orbital theory, predict the bond order for O2. 2 0.5 2.5 1 1.5

2

Based on molecular orbital theory, the bond order of the C-C bond in the C2 molecule is __________. 2 1 4 0 3

2

The combination of two atomic orbitals results in the formation of __________ molecular orbitals. 3 4 2 1 0

2

There are __________ unhybridized p atomic orbitals in an sp-hybridized carbon atom. 0 2 4 1 3

2

According to valence bond theory, which orbitals on bromine atoms overlap in the formation of the bond in Br2? 3s 3p 4s 3d 4p

4p

A typical double bond __________. consists of one σ bond and one π bond imparts rigidity to a molecule is stronger and shorter than a single bond All of these answers are correct. consists of two shared electron pairs

All of these answers are correct.

Of the molecules below, only __________ is polar. AsH3 SF6 SbF5 I2 CH4

AsH3

The energy-level diagram for molecular orbitals of second-row diatomic molecules predicts which of the following to be paramagnetic? O2, N2, B2 O2 only N2 and O2 B2 and O2 N2 and B2 N2 only

B2 and O2

In which molecule do we find bond angles of 109.5°? XeF4 CCl4 BF3 SF4 BrCl5

CCl4

Which of the following molecules contains polar bonds but is nonpolar? F2 NF3 CF4 H2O SO2

CF4

Which of the following is nonpolar? (i) CH4 (ii) CHBr3 (iii) CBr2Cl2 (iv) CH3Br CH4 CHBr3 CBr2Cl2 CH3Br All of the above are nonpolar.

CH4

Of the following, only __________ has sp2 hybridization of the central atom. PF5 PH3 I3 - ICl3 CO3 2-

CO3 2-

If we assume that the energy-level diagram for homonuclear diatomic molecules can be applied to heteronuclear diatomic molecules and ions, predict the bond order and magnetic behavior of the following: CO and OF. CO: bond order 2, diamagnetic; OF: bond order 1 1/2, diamagnetic CO: bond order 3, diamagnetic; OF: bond order 2, paramagnetic CO: bond order 3, diamagnetic; OF: bond order 1 1/2, paramagnetic CO: bond order 2, diamagnetic; OF: bond order 2, paramagnetic CO: bond order 3, paramagnetic; OF: bond order 1 1/2, paramagnetic

CO: bond order 3, diamagnetic; OF: bond order 1 1/2, paramagnetic

i and ii only

Dichloroethylene, C2H2Cl2, exists in three different forms (isomers), shown in the following figure: Which of these would have a nonzero dipole moment? iii only i only i and iii only i and ii only ii only

Give the total number of electron domains, the number of bonding and nonbonding domains, and the molecular geometry for PCl3. Three electron domains, three bonding domains, and zero nonbonding domains, trigonal planar Four electron domains, one bonding domain, and three nonbonding domains, linear Four electron domains, three bonding domains, and one nonbonding domains, trigonal pyramidal Four electron domains, three bonding domains, and one nonbonding domain, trigonal planar Four electron domains, two bonding domains, and two nonbonding domains, tetrahedral

Four electron domains, three bonding domains, and one nonbonding domains, trigonal pyramidal

n which one of the following are there five electron domains (bonding and nonbonding) around the central atom? ICl2 - AlCl6 3- PH4 + SiCl4 NF3

ICl2 -

Which identification of shape is incorrect? SeCl4 -- seesaw ClF5 -- square pyramidal SbCl5 -- trigonal bipyramidal ICl3 -- trigonal pyramidal AlCl63- -- octahedral

ICl3 -- trigonal pyramidal

The interaction between s and p molecular orbitals causes what changes in the molecular orbital diagram of a simple diatomic molecule? It lowers the energy of the sigma 2s orbital and raises the energy of the sigma 2p orbital. It lowers the energy of the pi 2p orbital. It has no effect on the diagram. It raises the energy of the sigma 2s and lowers the energy of the sigma 2p orbitals. It lowers the energy of the sigma 2s orbital only.

It lowers the energy of the sigma 2s orbital and raises the energy of the sigma 2p orbital.

Which one of the following is a polar molecule? BF3 CF4 NF3 PCl5 PCl5 NF3 CF4 BF3 All of the above are nonpolar.

NF3

Which of the following species would not have the MO configuration σ2/2s, σ⋅2/2s, σ2/2p, π4/2p? N2 NO+ Correct! NO CN- CO

NO

In which of the following do we find a trigonal-pyramidal geometry? TeCl4 SiO2 PH3 SnCl2 BF3

PH3

Which of the following molecules would be polar? SCO PCl5 CCl4 BCl3 CO2

SCO

Are σ bonds generally stronger or weaker than π bonds? Why? Stronger. There is less electron density between the atoms. Stronger. There is more electron density between the atoms. Weaker. There is more electron density between the atoms. Weaker. There is less electron density between the atoms.

Stronger. There is more electron density between the atoms.

sp2

The hybridization of the carbon atom labeled x in the molecule below is __________. sp3 sp sp3d2 sp3d sp2

120°

What are the bond angles about carbon in the following structure? 120° 180° 90° 60° 109.5°

trigonal planar

What is the geometry of the rightmost carbon atom in the molecule below? linear trigonal planar tetrahedral T-shaped trigonal bipyramidal

The addition of an electron to O2 and C2 will cause the bond order in the molecules to remain the same for both. increase for both. decrease for O2, increase for C2. increase for O2, decrease for C2. decrease for both.

decrease for O2, increase for C2.

The basis of the VSEPR model of molecular bonding is __________. regions of electron density on an atom will organize themselves so as to maximize s-character atomic orbitals of the bonding atoms must overlap for a bond to form regions of electron density in the valence shell of an atom will arrange themselves so as to maximize overlap electron domains in the valence shell of an atom will arrange themselves so as to minimize repulsions

electron domains in the valence shell of an atom will arrange themselves so as to minimize repulsions

Which molecule has a nitrogen atom with sp2 hybridization? nitromethane, CH3NO2 trimethylamine, :N(CH3)3 nitrosyl cation, NO+ acetonitrile, CH3C≡N: ammonium cation, NH4+

nitromethane, CH3NO2

According to MO theory, overlap of two p atomic orbitals produces __________. two π MOs, two π+ MOs, one σ MO, and one σ* MO one π and one π* MO or one σMO and one σ* MO one π+MO and one σ* MO one π MO and one σ⋅ MO one π MO and one σ MO

one π and one π* MO or one σMO and one σ* MO

Predict whether the SO2 and SO3 are polar or nonpolar molecules. polar, polar nonpolar, nonpolar nonpolar, polar polar, nonpolar impossible to tell

polar, nonpolar

Electrons in __________ bonds remain localized between two atoms. Electrons in __________ bonds can become delocalized between more than two atoms. sigma, pi ionic, sigma pi, sigma pi, pi sigma, sigma

sigma, pi

What is the hybridization of the carbon atom in carbon dioxide? sp3d sp2 sp sp3 sp3d2

sp

Indicate the designation for the hybrid orbitals formed from each of the following combinations of atomic orbitals: (i) one s and two p (ii) one s, three p, and one d sp2 and spd sp2 and sp2 d sp2 and sp 3d sp and sp2 d sp and

sp2 and sp 3d

The carbon-carbon σ bond in ethylene, CH2CH2, results from the overlap of __________. s atomic orbitals sp2 hybrid orbitals sp hybrid orbitals p atomic orbitals sp3 hybrid orbitals

sp2 hybrid orbitals

Indicate the hybrid-orbital set used by the central atom in each of the following polyatomic ions. (i) BH4 - (ii) PF6 - sp3 and sp3d2 sp3 and sp3d3 sp2 and sp3d2 sp3 and sp2d2 sp2 and sp2d2

sp3 and sp3d2

Which of the following shapes is not possible for a molecule in which the central atom has dsp3 hybridization? tetrahedral seesaw trigonal bipyramidal T-shaped linear

tetrahedral

Determine the shape and polarity of a COBr2 molecule. trigonal pyramidal, nonpolar tetrahedral, nonpolar trigonal planar, nonpolar trigonal planar, polar tetrahedral, polar

trigonal planar, polar

Determine the molecular shape of ClO3- from its Lewis structure. tetrahedral square planar trigonal pyramidal trigonal planar T-shaped

trigonal pyramidal

The molecular geometry of the PHCl2 molecule is __________. T-shaped tetrahedral bent trigonal pyramidal trigonal planar

trigonal pyramidal

sp, sp

The Lewis structure of carbon monoxide is given below. The hybridizations of the carbon and oxygen atoms in carbon monoxide are __________ and __________, respectively. sp, sp3 sp2, sp2 sp3, sp2 sp2, sp3 sp, sp

The valence shell electron pair repulsion (VSEPR) theory is based on the idea that - Nonbonded electron domains require less space than bonded electron domains. - The relative bond lengths in molecules determine the shape of the molecules. - The electron domains arrange themselves in such a fashion as to minimize the interaction between each domain. - The electron domains about an atom arrange themselves in such a fashion as to maximize the interaction between each domain. - Nonbonded electron domains require more space than bonded electron pairs.

The electron domains arrange themselves in such a fashion as to minimize the interaction between each domain.

SeF4

The image below depicts a seesaw structure. Which of the following has such a structure? XeF4 BrF4- BF4- SiF4 SeF4

SBr4

The image below depicts a tetrahedral structure. Which of the following does not have such a structure? AlCl4 - SiBr4 PH4 + SBr4 GeF4

trigonal planar

The molecular geometry of the right-most carbon in the molecule below is __________. trigonal bipyramidal T-shaped trigonal planar octahedral tetrahedral

Which hybrid-orbital set and molecular geometry are incorrect? dsp3 -- trigonal bipyramidal sp3 -- tetrahedral sp -- linear d2sp3 -- octahedral sp2 -- trigonal pyramidal

sp2 -- trigonal pyramidal

The electron-domain geometry of a sulfur-centered compound is trigonal pyramidal. The hybridization of the central sulfur atom is __________. sp3d sp sp3d2 sp2 sp3

sp3

The respective hybridizations of nitrogen in NF3 and NH3 are sp2 and sp2. sp3 and sp3. sp2 and sp3. sp3 and sp. sp and sp3.

sp3 and sp3

The electron-domain geometry of the AsF5 molecule is trigonal bipyramidal. The hybrid orbitals used by the As atom for bonding are __________ orbitals. sp3 sp2 sp2d2 sp3d2 sp3d

sp3d

What type of hybrid orbital is used for bonding by Xe in the XeF2 molecule? sp3 sp2 sp sp3d sp3d2

sp3d

According to VSEPR theory, if there are four electron domains in the valence shell of an atom, they will be arranged in a(n) __________ geometry. trigonal planar octahedral trigonal bipyramidal tetrahedral linear

tetrahedral

The blending of one s atomic orbital and two p atomic orbitals produces __________. three sp3 hybrid orbitals two sp2 hybrid orbitals three sp hybrid orbitals two sp3 hybrid orbitals three sp2 hybrid orbitals

three sp2 hybrid orbitals

How many σ and π bonds are in C2H2 in which the two carbons are adjacent and each carbon has one hydrogen? one σ bond and one π bond two σ bonds and one π bond four σ bonds and one π bond three σ bonds and two π bonds three σ bonds and one π bond

three σ bonds and two π bonds

Consider the following species when answering the following questions: (i) PCl3 (ii) CCl4 (iii) TeCl4 (iv) XeF4 (v) SF6 Which molecules are polar? (iv) and (v) (ii) and (iii) (i) and (iii) (iii) and (iv) (i) and (ii)

(i) and (iii)

Determine the angles between electron pairs about a central atom, given the following number of electron pairs: 2, 3. 2 -- 180°, 3 -- 120° 2 -- 109.5°, 3 -- 90° 2 -- 90°, 3 -- 90° 2 -- 90°, 3 -- 120° 2 -- 180°, 3 -- 109.5°

2 -- 180°, 3 -- 120°

Based on molecular orbital theory, the bond order of the N-N bond in the N2 molecule is __________. 3 0 5 1 2

3

Describe the characteristic electron-domain geometry of each of the following numbers of electron pairs about a central atom: 3, 4. 3 -- trigonal pyramidal, 4 -- tetrahedral 3 -- trigonal planar, 4 -- tetrahedral 3 -- bent, 4 -- trigonal planar 3 -- linear, 4 -- trigonal planar 3 -- trigonal planar, 4 -- bent 3 -- trigonal planar, 4 -- T-shaped

3 -- trigonal planar, 4 -- tetrahedral

Nine σ bonds and one π bond

Consider the Lewis structure for glycine, the simplest amino acid: What is the total number of σ bonds in the entire molecule, and what is the total number of π bonds? Six σ bonds and two π bonds Eight σ bonds and two π bonds Seven σ bonds and one π bond 14 σ bonds and one π bond Nine σ bonds and one π bond

Give the total number of electron domains, the number of bonding and nonbonding domains, and the molecular geometry for ClO2-. Two electron domains, two bonded domains, and zero nonbonding domains, linear Four electron domains, two bonded atoms, and two nonbonded electron domains, tetrahedral Four electron domains, one bonded domain, and three nonbonding electron domains, linear Two electron domains, two bonded atoms, and zero nonbonding domains, bent Four electron domains, two bonded atoms, and two nonbonded atoms, bent

Four electron domains, two bonded atoms, and two nonbonded atoms, bent

Arrange the following bonds in terms of decreasing strength (bond order): O2 +, O2, O2 -, O2 2-. O2 > O2 + > O2 - > O2 2- O2 - > O2 2- > O2 > O2 + O2 + > O2 > O2 2- > O2 - O2 + > O2 > O2 - > O2 2- O2 2- > O2- > O2 > O2 +

O2 + > O2 > O2 - > O2 2-

Which of the following ions are diamagnetic? N2 +, O2 2-, Be2 2+, O2 - N2 +, O2 2-, Be2 2+ N2 +, O2 2-, Be2 2+, O2 - N2 +, Be2 2+ O2 2-, Be2 2+, O2 - O2 2-, Be2 2+ N2 +, O2 -

O2 2-, Be2 2+

SCl2 has a nonzero dipole moment, but BeCl2 has a dipole moment of zero. How can you explain the difference? S is more electronegative than Be. S is more massive than Be. Be forms a double bond with one of the Cl atoms. S has two nonbonding pairs of electrons. S can expand its octet.

S has two nonbonding pairs of electrons.

Three monosulfur fluorides are observed: SF2, SF4, and SF6. Of these, __________ is/are polar. SF6 only SF2 only SF2, SF4, and SF6 SF2 and SF4 only SF4 only

SF2 and SF4 only

Which of the following molecules is/are polar? CCl4, SF4, CS2, NF3, SO3, PF5 CS2 and SF4 only CS2 and PF5 NF3 only PF5 only SF4 only Correct! SF4 and NF3 only

SF4 and NF3 only

SiF62- exists, but CF62- does not. Why? Use the concept of hybrid orbitals in your answer. Silicon is less electronegative, so its hybrid orbitals are lower in energy. Silicon is unusual, and hybridization is irrelevant. Carbon is never found in 2- ions. Silicon can hybridize using d orbitals not available in carbon. Carbon sp3 cannot accommodate six ligands.

Silicon can hybridize using d orbitals not available in carbon.