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Practice Exam - Frontier Orbitals; Self Dissociation; Formation of Halogen Cation, etc ...

1. Explain the following, with suitable examples:
a. Frontier orbitals
b. A 3-center 2e- bond
c. Tendency of P to form d pi -p pi bond
d. Self dissociation of ammonia
e. Formation of halogen cation

**Please see attachment for proper citation of symbols.


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The frontier orbitals are the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO). Example: Methylene belongs to the C2v point group. The HOMO and LUMO have, respectively, s-type (A1) and p-type (B2) symmetry and are separated by about 1 eV. Symmetric and antisymmetric combinations of these orbitals give the C-C bonding and antibonding orbitals of ethylene (ethene, C2H4). Ethene belongs to the D2h point group.

Compounds that contain fewer valence electrons than valence ...