Valence Electrons and Formal Charges

This video tutorial covers the drawing of Lewis structures for various polyatomic ions, including hydroxide, ammonium, methanide, iodine difluoride, and sulfur pentafluoride. It explains the importance of valence electrons and formal charges in determining the stability and structure of these ions. The tutorial emphasizes the need to adjust the number of valence electrons based on the ion's charge and highlights the role of formal charges in identifying which atoms carry the charge within the ion.

What is the total number of valence electrons in the hydroxide ion (OH-)?

• 6

• 7

• 9

• 8

In the hydroxide ion, which atom carries the formal negative charge?

• Neither

• Oxygen

• Hydrogen

• Both

How many valence electrons are available for distribution in the ammonium ion (NH4+)?

• 7

• 8

• 9

• 10

In the ammonium ion, what is the formal charge on the nitrogen atom?

• +2

• +1

• 0

• -1

How many bonds does the central carbon atom form in the methanide ion (CH3-)?

• 3

• 5

• 2

• 4

What is the formal charge on the central carbon atom in the methanide ion?

• +1

• 0

• +2

• -1

In the iodine difluoride cation, how many valence electrons are available for distribution?

• 21

• 20

• 19

• 18

Which atom carries the formal positive charge in the iodine difluoride cation?

• Iodine

• Neither

• Fluorine

• Both

How many valence electrons are distributed around the sulfur atom in the sulfur pentafluoride anion?

• 14

• 8

• 10

• 12

In the sulfur pentafluoride anion, which atom carries the formal negative charge?

• Both

• Neither

• Fluorine

• Sulfur