Molecular Geometry, using Orbital Hybridization
These notes should not replace the reading of good text books.
The basis for the Valence Bond theory: Sigma (s) bonds form by head on overlap of unhybridized, s-orbital-s-orbital, p-orbital-p-orbital, s-orbital-p-orbital and hybridized, (sp, sp²,sp³, sp³d and sp³d²) orbitals, strong bonds will form.
pi (p)-bonds form by side-ways overlap of unhybridized p- and d-orbitals, weak bonds will from.
Molecular Geometry (three dimensional structure) can be determined by the number of s-bonds and the lone pairs on the central atom. These lone pairs will also be accommodated in hybridized orbitals.

Orbitals used in bond formation	s-bond, showing the head on overlap of atomic orbitals
s-orbital - s-orbital
s-orbital - p-orbital
p-orbital - p-orbital
sp-hybrid orbital - sp-hybrid orbital or sp-hybrid - sp2 hybrid or sp2 hybrid - sp2 hybrid or sp2 hybrid - sp3 hybrid or sp2 hybrid - sp3d hybrid or sp3 hybrid - sp3d2 hybrid and so on	Two overlapping hybrids, forming a strong bond Hybridized orbitals will be simplified like so

Orbitals used in bond formation	p-bond, showing the side-ways overlap of atomic orbitals
py-orbital - py-orbital	overlap also illustrated like so
3dxy-orbital - py-orbital
3dxy-orbital - 3dxy-orbital

Hybridization and associated Molecular Geometry

Hybridization	Orbitals (simplified)	Molecular Geometry
sp	one s + one p :: two sp hybrids	Linear
sp2	one s + two p's :: 3 sp2 hybrids	Trigonal Planar
sp3	one s + three p's :: 4 sp3 hybrids	Tetrahedral
sp3d	one s + three p's + one d :: 5 sp3d hybrids	Trigonal Bipyramidal
sp3d2	one s + three p's + two d's :: 6 sp3d2 hybrids	Octahedral

Hybridization, Lone Pairs and associated Molecular Geometry
Molecular Geometry is determined by the positions of atomic nuclei in three dimensional space

Hybridization	Orbitals with LOne Pairs	Molecular Geometry
sp2	One Lone Pair in one of the sp2 hybrids	Bent
sp3	One Lone Pair in one of the sp3 hybrids	Trigonal Pyramidal
sp3	Two Lone Pairs in two of the sp3 hybrids	Bent
sp3d	One Lone Pair in one of the sp3d hybrids	See Saw
sp3d	Two Lone Pairs in two of the sp3d hybrids	T-Structure
sp3d	Three Lone Pairs in three of the sp3d hybrids	Linear
sp3d2	One Lone Pair in one of the sp3d2 hybrids	Square-pyramidal
sp3d2	Two Lone Pairs in two of the sp3d2 hybrids	Square-planar

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