Formal Charge and Lewis Structures

Dr. B explains how to draw the Lewis structure for the sulfite ion, SO3 2-. The video covers the total valence electrons, placing sulfur at the center, and arranging oxygen atoms around it. It discusses forming chemical bonds, ensuring each atom has an octet, and using all 26 valence electrons. The video also checks formal charges to determine the best structure, showing how to adjust the structure by forming a double bond to optimize formal charges. The final structure is presented with improved formal charges.

What is the total number of valence electrons in the SO3 2- ion?

• 26

• 30

• 28

• 24

Which element is placed at the center of the SO3 2- Lewis structure?

• Nitrogen

• Oxygen

• Sulfur

• Hydrogen

How many electrons are used to form chemical bonds between sulfur and oxygen in the initial structure?

• 8

• 6

• 10

• 4

What is the formal charge on the central sulfur atom in the initial Lewis structure?

• +1

• 0

• -1

• +2

What is the formal charge on each oxygen atom in the initial Lewis structure?

• -1

• -2

• +1

• 0

Why is it beneficial to form a double bond between sulfur and one of the oxygen atoms?

• To increase the total number of valence electrons

• To reduce the formal charge on sulfur to zero

• To make the structure more symmetrical

• To decrease the number of bonds

After forming a double bond, what is the formal charge on the sulfur atom?

• -1

• 0

• +1

• +2

What remains the formal charge on the other two oxygen atoms after forming a double bond?

• +1

• -2

• -1

• 0

What is the overall charge of the SO3 2- ion?

• 0

• -3

• -2

• -1

Why is the final Lewis structure considered better than the initial one?

• It uses fewer valence electrons

• It has more formal charges at zero

• It is more colorful

• It has more bonds