Chapter 10 Test

Question 1

What is the SN for the central nitrogen atom in azide ion, N3−?

Answer 1

2

Question 2

Which of the following is not a geometry observed for steric number = 4?

Answer 2

square planar

Question 3

Which of the following has bond angles of 109.5°?

Answer 3

SiF4

Question 4

The hydrogen atom, H, has an electron configuration of 1s1. It has one unpaired electron in its only electron orbital, 1s. The helium atom, He, has an electron configuration of 1s2. It has one pair of electrons in its only electron orbital (or shell), 1s. Why is hydrogen more likely to form H2 than helium is to form He2?

Answer 4

Helium atoms have a filled outer orbital (the s-orbital). There is no place for electron sharing that would have to occur to form He2. The outer orbital of the hydrogen atom is half-filled, which is ideal for electron sharing.

Question 5

The diagram shows the electron configuration for the carbon atom and for carbon as hybridized in the methane molecule. The hybridization of carbon results in the formation of which type of hybrid orbitals?

Answer 5

sp3 hybrid orbitals.

Question 6

The bonding in BF3 requires formation of hybrid orbitals on boron. If the molecule is oriented in the xy plane, what is the identity of the unfilled p orbital on boron?

Answer 6

2pz

Question 7

Which of the following statement is true regarding the paramagnetic property of O2 molecule and the diamagnetic property of N2?

Answer 7

The electronic configuration using the molecular orbital theory shows that O2 contains 2 unpaired electrons rendering it paramagnetic, while N2 contains no unpaired electrons and is thus diamagnetic.

Question 8

Use the diagram to decide which choice shows the correct orbital order for assigning electrons in HF.

Answer 8

2s site; σ site, two 2p sites; σ* site

Question 9

Which of the following is true regarding the bonding and hybridization of nitrogen in ammonia, NH3?

Answer 9

The 2s orbital and the three 2p orbitals undergo hybridization to form four sp3 hybrid orbitals. Three of the four sp3 orbitals forms a sigma bond with the three hydrogen atoms and the remaining orbital is filled with two electrons forming a nonbonding pair of electrons.

Question 10

Which statement best describes what happens to the carbon atom in formaldehyde as a result of the hybridization process?

Answer 10

Carbon’s 2s and 2p orbitals are hybridized, resulting in three hybrid sp2 orbitals and one (non-hybridized) pz orbital. Each new orbital has one lone electron assigned to it.

Question 11

Which statement about steric number is true?

Answer 11

The steric number is equal to the number of bonded atoms plus the number of lone pairs around a central atom

Question 12

What is the molecular geometry of the XeF2 molecule?

Answer 12

linear

Question 13

Identify all the polar molecule(s) from the following list.

CH4, CH3F, CH2F2, CHF3, CF4

Answer 13

CH3F, CH2F2, CHF3

Question 14

Which statement best explains why the molecule in the diagram is polar?

Answer 14

The molecule is linear but is polar because the electronegativity of oxygen is greater than the electronegativity of sulfur.

Question 15

Which of the following statements applies to antibonding molecular orbitals and not to bonding orbitals?

Answer 15

The wave functions add destructively between the two nuclei, resulting in a decrease in electron density between the nuclei.

Question 16

Which of the following chemical species has the strongest bond?

Answer 16

H2

Question 17

Which statement regarding the structure of benzene (shown below) is true?

Answer 17

The pi electrons are distributed over the entire molecule.

Question 18

Which statement best explains the idea of delocalized electrons?

Answer 18

Delocalized electrons are electrons that are spread out in a molecule (instead of being confined to atomic orbitals). This helps explain some of the unique physical properties (color, magnetism, and so on) of molecules.

Question 19

Which statement gives the best definition for isoelectronic molecules?

Answer 19

Isoelectronic molecules are molecules that have the same number of valence electrons and very similar orbitals that, as a result, give the molecules the same shape.

Question 20

What is the steric number for chlorine and geometry of the chlorine trifluoride (ClF3 ) molecule?

Answer 20

SN = 5, T-shaped

Question 21

In the molecule, SF2, what is the correct steric number for sulfur and what is the molecular geometry for the molecule?

Answer 21

SN = 4, bent

Question 22

Which of the following is required to form a bond in valence bond theory?

Answer 22

an unpaired electron on each atom

Question 23

What is the difference between a σ bond and a π bond?

Answer 23

A σ bond’s overlap occurs along the internuclear axis.

Question 24

Look at the diagram for the valence electron assignments for O2.

Which of the following answers correctly describes the species that have one unpaired electron?

Answer 24

O2+ and O2−

Question 25

Which orbital formation is shown in the diagram?

Answer 25

π* bond