Alevels : Chemical Bonding : Notes #3

Shapes of molecules:

VSEPR THEORY

VALENCE SHELL ELECTRON REPULSION THEORY.

shape of a molecule depends only on central atom and the lone pairs on central atom.

Case#》No# of lone pairs 》Bond angle 》Shape

AB2》 0 》180º 》 Linear

AB2》 1 》about 》120º 》Bent/ V shape

AB2 》2 》104.5º 》 Bent/ V shape

AB3 》0 》exactly 》120º 》Trigonal planner

AB3 》1 》107.5º 》Trigonal / Pyramidal

AB4 》0 》109.5º 》Tetrahedral

AB5 》0 》90º, 120º》 Bipyramidal

AB6 》0 》90º 》Octahedral

Shapes drawn:

Linear:

CO2

O=C=O

B—-A—-B

Bent/V shape:

Trigonal planner:

B
B—-A—-B

Trigonal / Pyramidal:

Tetrahedral:

Bipyramidal:

Octahedral: