linear - 2 electron pairs
triangular,- 3 electron pairs
tetrahedral - 4 electron pairs
trigonal bipyramidal 5 bond pairs,
octahedral – 6 bond pairs.
trigonal pyramidal - NH3 3 bp and one lp
To predict the shape of a molecule:
(1) Write down the Lewis dot structure for the molecule.
(2) Count the number of bond pairs and lone pairs around the central atom.
(3) Decide on the electron pair orientation based on the total number of electron pairs (4 = tetrahedral, 5 = trigonal bipyramidal).
(4) Consider the placement of lone pairs and any distortions from "regular" shapes.
(5) Name the shape based on the location of atoms (nuclei).