Logistics and Announcements

1
Logistics and Announcements

• Laboratory This Week
• Please come prepared!
• review lab procedure
• available at chem.allegheny.edu
• (on campus, type chem into URL field)
• No shorts or open-toed shoes (flip-flops are
  right out)
• Laboratory sales sponsored by CHEMII
• lab goggles, 14
• lab notebooks, 8
• model kits, 40

2
Topical Agenda

• Resonance Forms
• rules (brief review)
• octet expansion (brief elaboration)
• Bonding
• atomic orbitals
• hybrid orbitals
• molecular orbitals
• molecular shape

3
Lewis Structures
A. Octet Rules 1. Little octet rule all
things being equal, each atom should have an
octet
2. Big octet rule no row 2 element can
accommodate more than 8 electrons
4
Lewis Structures
B. Rules of Charge Separation 1. All
things being equal, structures should have
minimal charge separation
2. Any charge separation should be guided by
electronegativity trends
5
Molecular Orbitals of H2
s
E
s
6
Bonding in Ethene and Ethyne