|CH301H - Principles
of Chemistry I: Honors
Fall 2011, Unique 51040
Lecture Summary, 1 November 2011
|Atomic Orbital Hybridization:s
and p orbitals in the valence shell are close enough in energy that
they can mix to form a new set of atomic orbitals, called hybrids.
Hybrid orbitals allow atoms to form multiple bonds that are as
far apart from each other in space as possible, which allows the
molecule to achieve the lowest energy configuration. When
considering the 2s and 2p orbitals, the possible mixing that we achieve
depends on how many atoms or lone pairs the central atom is bonded to
(i.e. what we called the steric number back when talking about VSEPR).
SN AO's hybrids
2 s + p sp, sp
3 s + 2 p sp2, sp2, sp2
4 s + 3 p sp3, sp3, sp3, sp3
To first order these hybrid orbitals all look the same, and differ only how the are arranged around the central atom to maximize the space between them. The arrangement of hybrid orbitals around the central atom leads to the characteristic molecular geometries that we have already encountered when talking about VSEPR.