$$\text{Formal charge} = \text{valence electrons} - \text{nonbonding electrons} - \frac{1}{2} \times \text{bonding electrons}$$

$$\Delta H = \sum D(\text{bonds broken}) - \sum D(\text{bonds formed})$$

Question 1

Which of the following best describes the type of bonding in sodium chloride (NaCl)?

Accepted Answer

Ionic bonding, with electrons transferred from Na to Cl.

Question 2

According to the octet rule, which electron configuration do most atoms strive to achieve when forming chemical bonds?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^6$$

Question 3

Which of the following compounds will have the highest-magnitude lattice energy value?

Accepted Answer

LiBr

Question 4

Which factor has the greatest effect on the magnitude of lattice energy in an ionic compound?

Accepted Answer

The charge of the ions involved.

Question 5

Which pair of atoms forms the most polar bond?

Accepted Answer

N and F

Question 6

What is the formula for calculating the dipole moment ($$\mu) of a $$polar covalent bond?

Accepted Answer

$$\mu = Qr$$

Question 7

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

Accepted Answer

I$$_3^-$$

Question 8

Which statement about resonance structures is correct?

Accepted Answer

Resonance structures depict delocalized electrons that cannot be represented by a single Lewis structure.

Question 9

Which of the following is the best Lewis structure for the NCO$$^-$$ ion based on formal charges?

Accepted Answer

$$:\mathrm{N} \equiv \mathrm{C} - \mathrm{O}:$$

Question 10

Which of the following elements is most likely to expand its octet in a Lewis structure?

Accepted Answer

Phosphorus (P)

Question 11

Which of the following statements about bond order, bond length, and bond energy is correct?

Accepted Answer

As bond order increases, bond length decreases and bond energy increases.

Question 12

Which of the following best describes the difference between bonding pairs and lone pairs in a Lewis structure?

Accepted Answer

Bonding pairs are electrons shared between atoms; lone pairs are electrons not shared and belong to a single atom.

Question 13

Which of the following molecules is most likely to have resonance structures?

Accepted Answer

O$$_3$$

Question 14

Which of the following is true regarding the formal charge in a Lewis structure?

Accepted Answer

The sum of the formal charges must equal the net charge of the molecule or ion.

Question 15

Which of the following is a correct formula for calculating the formal charge of an atom in a molecule?

Accepted Answer

$$	ext{Formal charge} = 	ext{valence electrons} - 	ext{nonbonding electrons} - \frac{1}{2} 	imes 	ext{bonding electrons}$$

Question 16

Which of the following molecules is an exception to the octet rule because it has an odd number of electrons?

Accepted Answer

NO

Question 17

Which statement best explains why BF$$_3$$ does not follow the octet rule?

Accepted Answer

Boron is a Group IIIA element and is stable with only six valence electrons.

Question 18

Which of the following best describes the process of estimating the enthalpy change ($$\Delta H) of a $$reaction using bond energies?

Accepted Answer

$$\Delta H = \sum D(	ext{bonds broken}) - \sum D(	ext{bonds formed})$$

Question 19

Which of the following statements about electronegativity trends in the periodic table is correct?

Accepted Answer

Electronegativity increases from left to right across a period and from bottom to top within a group.

Chemical Bonding I: Types, Rules, and Structures

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