Formal Charges and Lewis Structures

Dr. B explains how to draw the Lewis structure for BCl3, starting with calculating the total valence electrons. Boron is placed at the center with Chlorines around it. The video explores the possibility of using double bonds and discusses the concept of formal charges to determine the most appropriate Lewis structure. The structure with the most formal charges closest to zero is identified as the best representation.

How many valence electrons does Boron have?

• 3

• 5

• 7

• 8

What is the total number of valence electrons in BCl3?

• 27

• 24

• 21

• 18

Where is Boron placed in the initial Lewis structure of BCl3?

• On the side

• At the bottom

• At the center

• At the top

Why doesn't Boron need to have a complete octet in BCl3?

• It has a high electronegativity

• It has more than 8 electrons

• It can form double bonds

• It is an exception to the octet rule

What is the purpose of introducing a double bond in BCl3?

• To increase the number of valence electrons

• To satisfy the octet rule for Boron

• To satisfy the octet rule for Chlorine

• To reduce the number of valence electrons

What is the formal charge of Chlorine in the initial BCl3 structure?

• +2

• -1

• 0

• +1

How is the formal charge of an atom calculated?

• Valence electrons minus half of bonding electrons

• Valence electrons minus bonding electrons

• Valence electrons minus nonbonding electrons minus half of bonding electrons

• Valence electrons minus nonbonding electrons

What is the formal charge of Boron in the BCl3 structure with a double bond?

• +1

• 0

• -1

• -2

Which Lewis structure is considered the best for BCl3?

• The one with the most double bonds

• The one with the most positive charges

• The one with formal charges closest to zero

• The one with the most negative charges

What is the formal charge of Chlorine in the final BCl3 structure?

• -1

• +2

• 0

• +1