Question 1

According to VSEPR theory, which of the following statements is always true regarding the shape of a molecule?

Accepted Answer

The shape is determined by repulsions among all electron groups on the central atom.

Question 2

A molecule contains three identical polar bonds in a trigonal planar molecular geometry. Is the molecule polar?

Accepted Answer

No, because the bond dipoles cancel due to the symmetry of the trigonal planar geometry.

Question 3

According to valence bond theory, what is a chemical bond?

Accepted Answer

The overlap between half-filled atomic orbitals on two atoms.

Question 4

How many $$sp^3$$ hybrid orbitals result from the hybridization of one s and three p orbitals?

Accepted Answer

4

Question 5

Which hybridization is associated with a trigonal planar electron geometry and what is the ideal bond angle?

Accepted Answer

$$sp^2$$, 120^\circ$

Question 6

Which of the following statements about sigma ($$\sigma) $$and pi ($$\pi) $$bonds is correct?

Accepted Answer

$$\sigma$$ bonds are stronger than $$\pi$$ bonds and allow free rotation.

Question 7

Which molecule is predicted to be diamagnetic based on its molecular orbital diagram?

Accepted Answer

$$N_2$$

Question 8

What is the bond order of the $$He_2$$ molecule according to molecular orbital theory?

Accepted Answer

$$0$$

Question 9

Which of the following best explains why rotation around a double bond is restricted?

Accepted Answer

Because of the presence of a $$\pi$$ bond, which would break upon rotation.

Question 10

Which hybridization scheme is used by the central atom in $$SF_6$$?

Accepted Answer

$$sp^3d^2$

Question 11

What is the bond order for $$O_2$$ using molecular orbital theory?

Accepted Answer

$$2$$

Question 12

Which of the following molecules is expected to be paramagnetic?

Accepted Answer

$$O_2$$

Question 13

Which of the following is a correct statement about hybrid orbitals?

Accepted Answer

The number of hybrid orbitals formed equals the number of atomic orbitals mixed.

Question 14

Which of the following best describes the bonding in ethyne ($$C_2H_2$$)?

Accepted Answer

Each carbon is $$sp$$ hybridized and forms two $$\pi$$ bonds and one $$\sigma$$ bond between the carbons.

Question 15

Which of the following is a real-world consequence of the restricted rotation around double bonds?

Accepted Answer

The existence of geometric (cis/trans) isomers in alkenes.

Question 16

What is the bond order of $$H_2$$^+$$ according to molecular orbital theory?

Accepted Answer

$$\frac{1}{2}$$

Question 17

Which of the following statements about molecular orbital (MO) theory is correct?

Accepted Answer

MO theory predicts magnetic properties and delocalization of electrons.

Question 18

Which of the following is true about the bond order and stability of $$Be_2$$?

Accepted Answer

Bond order is 0, so $$Be_2 is $$not stable.

Question 19

Which of the following best describes the difference between valence bond (VB) theory and molecular orbital (MO) theory?

Accepted Answer

MO theory accounts for electron delocalization, while VB theory assumes electrons are localized.

Question 20

Which of the following is a correct application of the bond order formula $$	ext{Bond order} = \frac{1}{2}(	ext{# Bonding Electrons} - 	ext{# Antibonding Electrons})$$ for $$Li_2$$?

Accepted Answer

$$\frac{1}{2}(2-0) = 1$$

CHEM 131 Chapter 11 Pt. 2: Chemical Bonding II: Valence Bond Theory and Molecular Orbital Theory

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