Sunday, February 3, 2008

JEE Revision - Shapes of Molecules

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

square planar,
square pyramidal,

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).

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