$$\text{Formal charge} = \text{valence electrons} - (\text{lone pair electrons} + \frac{1}{2} \times \text{bonding electrons})$$

$$\Delta H = \sum BE(\text{reactants}) - \sum BE(\text{products})$$

Question 1

Which of the following best describes a coordinate covalent bond?

Accepted Answer

A bond in which both electrons in the shared pair are donated by one atom.

Question 2

Which molecule violates the octet rule due to having an odd number of electrons?

Accepted Answer

NO

Question 3

Given the following electronegativities: F = 4.0, O = 3.5, N = 3.0, C = 2.5, which bond is expected to be the most polar?

Accepted Answer

C–F

Question 4

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

Accepted Answer

$$	ext{Formal charge} = 	ext{valence electrons} - (	ext{lone pair electrons} + \frac{1}{2} 	imes 	ext{bonding electrons})$$

Question 5

Which of the following statements about lattice energy is correct?

Accepted Answer

Lattice energy increases as the charge of the ions increases and the size of the ions decreases.

Question 6

Which of the following molecules is expected to have resonance structures?

Accepted Answer

NO$$_3^-$$

Question 7

What is the bond order of the carbon-oxygen bonds in CO$$_2$$?

Accepted Answer

2

Question 8

Which of the following best explains why metals conduct electricity?

Accepted Answer

Valence electrons are delocalized and move freely throughout the metallic lattice.

Question 9

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

Accepted Answer

Carbon in CH$$_4$$

Question 10

Which of the following best describes a resonance hybrid?

Accepted Answer

A structure that is an average of all possible resonance forms.

Question 11

Which of the following molecules contains a coordinate covalent bond?

Accepted Answer

NH$$_4^+$$

Question 12

Which of the following is the correct expression for the enthalpy change ($$\Delta H) of a $$reaction using bond energies?

Accepted Answer

$$\Delta H = \sum BE(	ext{reactants}) - \sum BE(	ext{products})$$

Question 13

Which of the following best describes the relationship between bond order and bond length?

Accepted Answer

As bond order increases, bond length decreases.

Question 14

Which of the following is the correct definition of electronegativity?

Accepted Answer

The ability of an atom in a molecule to attract shared electrons to itself.

Question 15

Which of the following species can have an expanded valence shell?

Accepted Answer

SF$$_6$$

Question 16

Which of the following is true about bond dissociation energy?

Accepted Answer

It is the energy required to break one mole of a particular bond in a gaseous species.

Question 17

Which of the following molecules is most likely to be electron deficient?

Accepted Answer

BF$$_3$$

Question 18

Which of the following is the correct order of increasing lattice energy for LiF, KCl, and KI?

Accepted Answer

KI \u003c KCl \u003c LiF

Question 19

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

Accepted Answer

Resonance structures represent different possible arrangements of electrons, not atoms.

Question 20

Which of the following is the best criterion for selecting the most reasonable Lewis structure for a molecule?

Accepted Answer

The structure with the smallest formal charges and negative charges on the most electronegative atoms.

Chemical Bonding I: Lewis Theory – Comprehensive Study Notes

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