$$\text{FC} = \text{VE} - \text{NE} - (\text{BE}/2)$$

Question 1

Which of the following statements about formal charge is TRUE?

Accepted Answer

The sum of the formal charges in a neutral molecule must be zero.

Question 2

Given the thiocyanate ion (SCN$$^-$$), which Lewis structure is the dominant one based on formal charges?

Accepted Answer

The structure where S has $$-1$$, C has $$0$$, and N has $$0.$$

Question 3

Which molecule is an example of an expanded octet?

Accepted Answer

PF$$_5$$

Question 4

Which of the following molecules is an example of a compound with fewer than eight electrons around the central atom?

Accepted Answer

BF$$_3$$

Question 5

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

Accepted Answer

Molecules with exactly eight electrons

Question 6

How many equivalent resonance forms can be drawn for the carbonate ion, CO$$_3$$^{2-}$$, with carbon as the central atom?

Accepted Answer

3

Question 7

Which statement best describes resonance structures?

Accepted Answer

Resonance structures are multiple Lewis structures for a single molecule, and the actual structure is an average of all possible structures.

Question 8

Which property is NOT characteristic of ionic substances?

Accepted Answer

Covalent bonding

Question 9

Which process in the Born–Haber cycle is exothermic?

Accepted Answer

Formation of the solid ionic compound from gaseous ions

Question 10

Which factor increases the lattice energy of an ionic compound?

Accepted Answer

Increasing the charge on the ions

Question 11

Which of the following best explains why the formation of NaCl from sodium and chlorine is highly exothermic?

Accepted Answer

Energy is released when the solid NaCl forms from gaseous ions.

Question 12

Which of the following molecules has the shortest carbon-carbon bond length?

Accepted Answer

H–C≡C–H

Question 13

Which statement about bond enthalpy and bond length is correct?

Accepted Answer

Bond enthalpy increases as bond length decreases.

Question 14

A molecule has an odd number of electrons. Which of the following is TRUE?

Accepted Answer

It is likely to be unstable and highly reactive.

Question 15

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

Accepted Answer

$$	ext{FC} = 	ext{VE} - 	ext{NE} - (	ext{BE}/2)$$

Question 16

Which of the following best describes the electron transfer in the formation of NaCl?

Accepted Answer

Na loses an electron to Cl.

Question 17

Which of the following ions would have the highest lattice energy?

Accepted Answer

LiCl

Question 18

Which of the following is a consequence of resonance in the ozone molecule (O$$_3$$)?

Accepted Answer

The electron density is distributed symmetrically across the molecule.

Question 19

Which of the following statements about the Born–Haber cycle is correct?

Accepted Answer

The lattice energy is the energy released when one mole of a solid ionic compound is separated into its gaseous ions.

Question 20

Which of the following is a real-world application of lattice energy?

Accepted Answer

Predicting the solubility of salts in water.

Chemical Bonding: Formal Charge, Resonance, Octet Rule Exceptions, and Ionic Bonding

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