Transcript Chemistry 111

Chemistry 111
Sections 12.1 – 12.2
Chemistry 111
1
Review Chapter 11
• Spend 15-20 productive minutes
reviewing the material from Chapter 11.
• Check your chapter notes! Compare
yours & your team’s.
• Compare to the lecture notes.
2
Making Your Own Lewis Diagrams
• There are two main approaches to
making Lewis Diagrams:
– Start with atoms, share & trade electrons
– Count all valence electrons, use a system.
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Method #1 – Share & Error
• Draw a Lewis Diagram for HCl
• Step 1: Draw Atomic Lewis Dots
H
Cl
• Step 2: Find a way to share electrons to get
octets:
H
Cl
H
Cl
• Notes: This works until you get to complex
situations – then you have to think harder.
• You are allowed to do it this way if you like it. Give the other
way a try?
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Method #2 - Systematic
• This method never fails with non-octet
exceptions.
• You have to invest time learning the system –
then it’s a no-brainer
– This works well for me…
– Maybe good when you’re stressed on an exam?
• No matter what, we need to be good w/
Lewis Diagrams for most of the quarter’s
chemistry.
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Systematic Steps (Overview)
1.
2.
3.
4.
Count all valence electrons
Choose center atom
Draw a guess for the structure
Audit the structure
1. If necessary, fix the guess
5. Perform a Final Check
HANDOUT!
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