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

$\text{Formal Charge} = \text{Valence electrons} - \text{Lines} - \text{Dots}$

Question 1

Which of the following is the correct Lewis structure for $\mathrm{N_2}$?

Accepted Answer

$\mathrm{N\equiv N}$ with one lone pair on each N

Question 2

How many total valence electrons are present in the Lewis structure of $\mathrm{XeF_2}$?

Accepted Answer

$20$

Question 3

Which resonance structure contributes more to the actual structure of $\mathrm{CO_2}$?

Accepted Answer

$\mathrm{O=C=O}$ with zero formal charges on all atoms

Question 4

What is the formal charge on the oxygen atom in water ($\mathrm{H_2O}$)?

Accepted Answer

$0$

Question 5

Given the formula for formal charge: $	ext{Formal Charge} = 	ext{Valence electrons} - 	ext{Lines} - 	ext{Dots}$, what is the formal charge on the central carbon in $\mathrm{CO_2}$?

Accepted Answer

$0$

Question 6

Which guideline is most important when selecting the best Lewis structure among possible resonance forms?

Accepted Answer

The structure with the most atoms having zero formal charge

Question 7

In the Lewis structure of $\mathrm{XeF_2}$, how many lone pairs are present on the xenon atom?

Accepted Answer

3

Question 8

Which of the following statements about formal charge is correct?

Accepted Answer

Formal charge helps predict the most stable resonance structure

Question 9

For the molecule $\mathrm{OF}$, which Lewis structure is preferred based on formal charges?

Accepted Answer

Structure with zero formal charges on both O and F

Question 10

Which of the following is a correct application of the formal charge formula for the oxygen atom in $\mathrm{H_2O}$?

Accepted Answer

$6 - 2 - 4 = 0$

Question 11

Why are negative formal charges preferred on more electronegative atoms in Lewis structures?

Accepted Answer

Because electronegative atoms stabilize negative charge better

Question 12

Which of the following is NOT a guideline for selecting the best Lewis structure?

Accepted Answer

Structures with adjacent atoms having the same formal charge are preferred

Question 13

A molecule has two resonance structures. Structure A has all atoms with zero formal charge, while Structure B has a $-1$ formal charge on one atom and $+1$ on another. Which structure is more stable?

Accepted Answer

Structure A

Question 14

Calculate the formal charge on nitrogen in $\mathrm{NO}$, given that N is in group 15 and O in group 16. The Lewis structure has N with one lone pair and two bonds to O.

Accepted Answer

$-1$

Question 15

Which of the following molecules is most likely to have a central atom with an expanded octet?

Accepted Answer

$\mathrm{XeF_2}$

Question 16

If a Lewis structure has adjacent atoms with both positive formal charges, what does this indicate about the stability of the structure?

Accepted Answer

It is less stable

Question 17

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

Accepted Answer

$	ext{Formal Charge} = 	ext{Valence electrons} - 	ext{Lines} - 	ext{Dots}$

Question 18

In the Lewis structure of $\mathrm{CO_2}$, what is the formal charge on each oxygen atom?

Accepted Answer

$0$

Question 19

A student draws a Lewis structure for $\mathrm{NO}$ with N having three bonds and no lone pairs. What is the formal charge on N?

Accepted Answer

$+1$

Covalent Bonding and Electron-Dot Structures: Formal Charge and Resonance

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