$$\text{Formal charge} = \text{valence electrons of lone atom} - (\text{number of dots and bonds around atom in molecule})$$

Question 1

Which of the following bonds is expected to be the most polar based on electronegativity differences?

Accepted Answer

$$\mathrm{O-H}$$

Question 2

Which of the following elements can form compounds with expanded octets?

Accepted Answer

$$\mathrm{P}$$

Question 3

Consider the molecule $$\mathrm{BF_3$}. $$Which statement is correct regarding its Lewis structure and octet rule?

Accepted Answer

Boron has an incomplete octet with only six electrons around it.

Question 4

Which of the following molecules is polar?

Accepted Answer

$$\mathrm{$$OCCl_2$$}$$

Question 5

What is the formal charge on the central atom in the Lewis structure of $$\mathrm{NO_3$^-} ($$nitrate ion)?

Accepted Answer

$$0$$

Question 6

Which of the following statements about resonance structures is TRUE?

Accepted Answer

The resonance hybrid is an average of all possible resonance structures.

Question 7

Which compound has the weakest carbon–carbon bond?

Accepted Answer

$$\mathrm{CH_3CH_3}$$

Question 8

What is the hybridization of the central atom in $$\mathrm{SF_6$}$$?

Accepted Answer

$$\mathrm{sp^3$d^2$$}$

Question 9

How many sigma ($$\sigma) $$and pi ($$\pi) $$bonds are present in the molecule propyne ($$\mathrm{$$HCCCH_3$$}$$)?

Accepted Answer

6 $$\sigma$$, 2 $$\pi$$

Question 10

Why is rotation restricted around a carbon–carbon double bond?

Accepted Answer

Because the double bond contains a $$\pi$$ bond that would be broken upon rotation.

Question 11

Which of the following best describes the bond order in the resonance hybrid of $$\mathrm{$$ClO_3$$^-}$$?

Accepted Answer

Each Cl–O bond has a bond order of $$\dfrac{5}{3}.$$

Question 12

Which of the following molecules has a tetrahedral molecular geometry?

Accepted Answer

$$\mathrm{CH_4$}$$

Question 13

What is the bond order of $$\mathrm{O_2$}$$ according to molecular orbital theory?

Accepted Answer

$$2$$

Question 14

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

Accepted Answer

$$\mathrm{O_2$}$$

Question 15

Which of the following statements about nonbonding molecular orbitals is correct?

Accepted Answer

They are localized on one atom and do not contribute to bond order.

Question 16

A molecule has 3 bonding groups and 1 lone pair on the central atom. What is its molecular geometry and approximate bond angle?

Accepted Answer

Trigonal pyramidal, $$107^\circ$$

Question 17

Which of the following best explains why $$\mathrm{CO_2$} is a $$nonpolar molecule?

Accepted Answer

The molecule is linear and the bond dipoles cancel.

Question 18

Which of the following is the correct formula for calculating formal charge?

Accepted Answer

$$	ext{Formal charge} = 	ext{valence electrons of lone atom} - (	ext{number of dots and bonds around atom in molecule})$$

Question 19

Which of the following statements about hybridization is correct?

Accepted Answer

A central atom with 5 electron groups is $$\mathrm{sp^3$d}$$ hybridized.

Question 20

Which of the following best describes an isomer?

Accepted Answer

A molecule with the same molecular formula but different connectivity of atoms.

Study Guide: Chemical Bonding I & II (Chapters 5 and 6)

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