Formal Charge and Stability Concepts

This video provides a comprehensive introduction to formal charge, explaining how to calculate it using a simplified formula. It includes examples with nitrogen, hydronium ion, sulfur dioxide, cyanide ion, and ammonium ion, demonstrating how to determine the formal charge of atoms in different molecules. The video also covers the concept of resonance and how formal charge can help identify the most stable Lewis structure. Through practice problems, viewers learn to apply the formula and understand the significance of formal charge in molecular stability.

What is the formula for calculating the formal charge of an atom?

• Number of lone pairs minus valence electrons

• Valence electrons minus the sum of bonds and lone pairs

• Number of bonds minus valence electrons

• Valence electrons plus the sum of bonds and lone pairs

In the example of nitrogen, what is the formal charge when it has two bonds and four dots?

• +1

• -1

• 0

• +2

For the hydronium ion, what is the formal charge on the oxygen atom?

• +2

• -1

• 0

• +1

In sulfur dioxide, what is the formal charge on the sulfur atom?

• -1

• 0

• +1

• +2

What is the formal charge on the oxygen atom on the right in sulfur dioxide?

• 0

• +2

• -1

• +1

In the cyanide ion, which element bears the negative charge?

• Carbon

• Neither

• Nitrogen

• Both

What is the formal charge on nitrogen in the ammonium ion (NH4+)?

• +2

• 0

• -1

• +1

Which element is more electronegative, making it preferable to bear a negative charge in a Lewis structure?

• Carbon

• Sulfur

• Oxygen

• Nitrogen

In the OCN- ion, which structure is the most stable based on formal charge?

• Structure with negative charge on nitrogen

• Structure with negative charge on oxygen

• Structure with negative charge on carbon

• All structures are equally stable

What percentage of the resonance hybrid does the most stable structure of OCN- represent?

• 95%

• 10%

• 25%

• 50%