Q: Which of the following is the correct formula for calculating the formal charge on an atom?

$$\text{Formal charge} = \text{group number} - [\text{number of lone electrons} + \frac{1}{2}(\text{number of bonding electrons})]$$

Question 1

Which of the following statements best explains why energy is released when a chemical bond is formed?

Accepted Answer

Because the system achieves a lower energy state, and the excess energy is released.

Question 2

According to Coulomb’s Law, which combination of ion charges and distances will result in the strongest ionic bond?

Accepted Answer

$$Q_1 = +2$, Q_2$ = -2$$, $$r = 0.2 nm$$

Question 3

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

Accepted Answer

F–H

Question 4

Which molecule violates the octet rule by having fewer than eight electrons around the central atom?

Accepted Answer

BeCl$$_2$$

Question 5

What is the bond order of the carbonate ion ($$\mathrm{CO_3$^{2-}}$$)?

Accepted Answer

$$3/2$$

Question 6

Which of the following best describes the molecular geometry of water ($$\mathrm{H_2O}$$)?

Accepted Answer

Bent (V-shaped)

Question 7

Which of the following molecules is nonpolar, despite having polar bonds?

Accepted Answer

CO$$_2$$

Question 8

Which of the following is a correct statement about bond energy and bond order?

Accepted Answer

Bond energy increases as bond order increases.

Question 9

Given the reaction: $$\mathrm{CH_4$(g) + 2Cl_2(g) + 2F_2(g) \rightarrow CF_2Cl_2(g) + 2HF(g) + 2HCl(g)}$$, which step is required to calculate $$\Delta H$$ using bond energies?

Accepted Answer

Subtract the energies of bonds formed from the energies of bonds broken.

Question 10

Which of the following molecules has a square planar molecular geometry?

Accepted Answer

XeF$$_4$$

Question 11

Which of the following best describes the bonding in metallic substances?

Accepted Answer

A sea of delocalized electrons surrounds positively charged metal ions.

Question 12

Which of the following is true about resonance structures?

Accepted Answer

They differ in the positions of the electron pairs.

Question 13

Which of the following molecules contains a coordinate covalent bond?

Accepted Answer

NH$$_4^+$$

Question 14

Which of the following best explains why ionic compounds have high melting points?

Accepted Answer

They have strong electrostatic attractions between ions.

Question 15

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

Accepted Answer

$$	ext{Formal charge} = 	ext{group number} - [	ext{number of lone electrons} + \frac{1}{2}(	ext{number of bonding electrons})]$$

Question 16

Which of the following molecules is expected to have a dipole moment?

Accepted Answer

H$$_2S$$

Question 17

Which of the following best describes the geometry of PCl$$_5 in $$the gas phase?

Accepted Answer

Trigonal bipyramidal

Question 18

Which of the following statements about the octet rule is correct?

Accepted Answer

Elements in period 3 or higher can have more than eight electrons in their valence shell.

Question 19

Which of the following bonds is the shortest according to Table 8.5?

Accepted Answer

C≡N triple bond

Question 20

Which of the following best describes the effect of lone pairs on bond angles in molecules?

Accepted Answer

Lone pairs decrease bond angles between atoms.

Chemical Bonding and Molecular Structure: Study Guide

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