Q: Arrange the following bonds in order of increasing polarity, using electronegativity differences: C–N, Na–F, O–H.

$\mathrm{C-N} < \mathrm{O-H} < \mathrm{Na-F}$

Q: Which rule should be used to select the best Lewis structure when multiple are possible?

Choose the structure with the lowest magnitudes of formal charges.

Q: Bond order is defined as:

The number of pairs of electrons in a bond.

Q: Which statement is true about bond length and bond order?

Bond length decreases as bond order increases.

Q: Bond enthalpy is best described as:

The average enthalpy change for breaking a specific bond in a molecule in the gas phase.

Q: Which of the following statements about formal charge is correct?

Formal charge is calculated by assuming bonding electrons are equally shared between bonded atoms.

Question 1

Which of the following statements best describes a polar covalent bond?

Accepted Answer

A bond in which the bonding electrons spend more time near one atom than the other.

Question 2

Electronegativity is most closely related to which two atomic properties?

Accepted Answer

Ionization energy and electron affinity.

Question 3

Which of the following elements has the highest electronegativity?

Accepted Answer

Fluorine (F)

Question 4

Given the electronegativities: $X_{Cl} = 3.0$, $X_H = 2.1$, in the H–Cl bond, which atom acquires a partial negative charge?

Accepted Answer

Chlorine (Cl)

Question 5

Arrange the following bonds in order of increasing polarity, using electronegativity differences: C–N, Na–F, O–H.

Accepted Answer

$\mathrm{C-N} < \mathrm{O-H} < \mathrm{Na-F}$

Question 6

How many valence electrons are present in the Lewis structure of $\mathrm{OF_2}$?

Accepted Answer

20

Question 7

Which of the following molecules is an exception to the octet rule because it has fewer than eight electrons around the central atom?

Accepted Answer

$\mathrm{BF_3}$

Question 8

Which molecule below can have more than eight electrons around its central atom due to the presence of d subshells?

Accepted Answer

$\mathrm{PF_5}$

Question 9

What is the formal charge on the central carbon atom in the left Lewis structure of $\mathrm{CO_2}$?

Accepted Answer

0

Question 10

Which rule should be used to select the best Lewis structure when multiple are possible?

Accepted Answer

Choose the structure with the lowest magnitudes of formal charges.

Question 11

In the Lewis structure of $\mathrm{H_2SO_4}$, what is the formal charge on the sulfur atom when all bonds are single?

Accepted Answer

+2

Question 12

Which molecule below exhibits resonance due to delocalized bonding?

Accepted Answer

$\mathrm{CH_3COO^-}$

Question 13

Bond order is defined as:

Accepted Answer

The number of pairs of electrons in a bond.

Question 14

Which statement is true about bond length and bond order?

Accepted Answer

Bond length decreases as bond order increases.

Question 15

Consider the molecules $\mathrm{N_2H_4}$, $\mathrm{N_2}$, and $\mathrm{N_2F_2}$. Which has the shortest nitrogen-nitrogen bond?

Accepted Answer

$\mathrm{N_2}$

Question 16

Bond enthalpy is best described as:

Accepted Answer

The average enthalpy change for breaking a specific bond in a molecule in the gas phase.

Question 17

Given the following bond energies: $\mathrm{C=C}$ (602 kJ), $\mathrm{C-Cl}$ (240 kJ), $\mathrm{C-C}$ (346 kJ), $\mathrm{C-Cl}$ (654 kJ), calculate $\Delta H$ for the reaction: $\mathrm{C_2H_4} + Cl_2 ightarrow C_2H_4Cl_2$ using $\Delta H = 	ext{bonds broken} - 	ext{bonds formed}$.

Accepted Answer

$\Delta H = -158\ \mathrm{kJ}$

Question 18

Which of the following is NOT a valid exception to the octet rule?

Accepted Answer

$\mathrm{CH_4}$

Question 19

Which of the following statements about formal charge is correct?

Accepted Answer

Formal charge is calculated by assuming bonding electrons are equally shared between bonded atoms.

Question 20

In the Lewis structure of $\mathrm{IF_5}$, how many valence electrons are present?

Accepted Answer

42

Polar Covalent Bonds, Electronegativity, and Lewis Structures - Chapter 10 - Part 2

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