Q: What is the formula for calculating the formal charge of an atom in a Lewis structure?

$\text{Formal Charge} = \text{Valence Electrons} - (\text{Nonbonding Electrons} + \frac{1}{2} \times \text{Bonding Electrons})$

Question 1

Which of the following elements is most likely to form an incomplete octet in a stable compound?

Accepted Answer

Boron ($\mathrm{B}$)

Question 2

What is the formal charge on the nitrogen atom in the ammonium ion ($\mathrm{NH_4^+}$)?

Accepted Answer

$+1$

Question 3

Which of the following best describes the electrons involved in metallic bonding?

Accepted Answer

Valence electrons that move freely between metal ions.

Question 4

Calculate the difference in electronegativity values between carbon and fluorine.

Accepted Answer

$1.5$

Question 5

Which of the following molecules has the largest dipole moment?

Accepted Answer

$\mathrm{HCl}$

Question 6

What is the average bond order of the sulfur-oxygen bonds in the sulfate ion ($\mathrm{SO_4^{2-}}$)?

Accepted Answer

$1.5$

Question 7

Which compound would you expect to have the highest melting point according to the ionic bonding model?

Accepted Answer

$\mathrm{AlF_3}$

Question 8

Which of the following statements is true regarding the relationship between bond length and bond strength for a series of compounds including bonds between the same two atoms?

Accepted Answer

The greater the bond strength, the shorter the bond.

Question 9

Using the Born-Haber cycle, how many ionization energies (IE) and electron affinities (EA) are needed for the formation of $\mathrm{K_2O}$?

Accepted Answer

2 IE, 1 EA

Question 10

Which element in the thiocyanate ion ($\mathrm{NCS^-}$) possesses a negative charge based on formal charge calculations?

Accepted Answer

Sulfur ($\mathrm{S}$)

Question 11

Which of the following species has bonds with the most ionic character?

Accepted Answer

$\mathrm{NaCl}$

Question 12

What is the formal charge on the central carbon atom in carbon monoxide ($\mathrm{CO}$)?

Accepted Answer

$-1$

Question 13

Which of the following molecules is most likely to have an expanded octet?

Accepted Answer

$\mathrm{SF_6}$

Question 14

Which compound possesses the strongest ionic bond: $\mathrm{MgF_2}$ or $\mathrm{KCl}$?

Accepted Answer

$\mathrm{MgF_2}$

Question 15

How many lone pairs does the sulfur atom possess in the hydrogen sulfide molecule ($\mathrm{H_2S}$)?

Accepted Answer

2

Question 16

Which of the following best describes the physical property attributed to metallic bonding?

Accepted Answer

Conductivity

Question 17

What is the formula for calculating the formal charge of an atom in a Lewis structure?

Accepted Answer

$	ext{Formal Charge} = 	ext{Valence Electrons} - (	ext{Nonbonding Electrons} + \frac{1}{2} 	imes 	ext{Bonding Electrons})$

Question 18

Which of the following molecules contains the greatest number of sigma ($\sigma$) bonds?

Accepted Answer

Ethane ($\mathrm{C_2H_6}$)

Question 19

Which of the following is a correct statement about the lattice energy of ionic crystals?

Accepted Answer

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

Question 20

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond in which electrons are shared unequally between two atoms due to a difference in electronegativity.

Chapter10 Study Notes: Chemical Bonding I – The Lewis Model

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