$FC = \text{number of valence electrons} - \text{number of bonds} - \text{number of lone pair electrons}$

Question 1

Which of the following elements typically forms only one bond in covalent compounds due to its need to achieve a duet rather than an octet?

Accepted Answer

Hydrogen

Question 2

What is the bond order of the carbon-nitrogen triple bond in the molecule HC≡N?

Accepted Answer

$3$

Question 3

Which statement best describes the relationship between bond order, bond length, and bond strength?

Accepted Answer

Higher bond order means shorter bond length and higher bond strength.

Question 4

In the nitrate ion ($NO_3^-$), what is the average bond order for the N–O bonds?

Accepted Answer

$1.33$

Question 5

Which of the following is a correct statement about formal charges in dominant resonance forms?

Accepted Answer

Dominant resonance forms have formal charges between -1, 0, and +1.

Question 6

Which element below can have an expanded octet in its Lewis structure?

Accepted Answer

Sulfur

Question 7

A molecule has 17 valence electrons. Which of the following is true about its Lewis structure?

Accepted Answer

The molecule will be a radical with one atom having an unpaired electron.

Question 8

Which of the following is the correct bond order for the carbonate ion ($CO_3^{2-}$)?

Accepted Answer

$1.5$

Question 9

In the Lewis structure of $H_2O$, how many lone pairs are present on the oxygen atom?

Accepted Answer

Two

Question 10

Which of the following molecules is most likely to have a central atom with an incomplete octet?

Accepted Answer

$BF_3$

Question 11

Which of the following is true about the placement of hydrogen atoms in the Lewis structures of oxyacids?

Accepted Answer

Hydrogen atoms are bonded to oxygen atoms.

Question 12

Which of the following is a correct statement about resonance structures?

Accepted Answer

Electrons move between resonance forms, but atom positions remain fixed.

Question 13

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

Accepted Answer

$FC = 	ext{number of valence electrons} - 	ext{number of bonds} - 	ext{number of lone pair electrons}$

Question 14

Which of the following ions has a bond order of $1.5$ for its central atom's bonds?

Accepted Answer

$CO_3^{2-}$

Question 15

Which of the following is a correct statement about the line bond structure used in organic chemistry?

Accepted Answer

It omits external hydrogens and lone pairs for simplicity.

Question 16

Which of the following molecules contains a central atom that can have more than 8 electrons in its valence shell?

Accepted Answer

$PCl_5$

Question 17

Which of the following is true about the formal charge distribution in dominant resonance forms?

Accepted Answer

Negative formal charges are placed on the most electronegative atoms.

Question 18

Which of the following best explains why $NO$ is considered a radical?

Accepted Answer

It has an odd number of valence electrons, resulting in one unpaired electron.

Question 19

Which of the following statements about bond strength is correct?

Accepted Answer

Triple bonds require more energy to break than single bonds.

Question 20

Which of the following is the correct bond order for the sulfate ion ($SO_4^{2-}$)?

Accepted Answer

$1.5$

Bonding Trends, Lewis Structures, and Resonance: Key Concepts and Exceptions

Study Guide - Practice Questions