They are AB 2 type molecules in which the central atom has no lone pairs. To avoid repulsions between the bonding pairs, arrange the B groups as far apart as possible.

An example is beryllium dichloride, BeCl 2 .

The molecule is linear with bond angles of 180º.

A second example is the carbon dioxide molecule, CO 2

Carbon dioxide arranges the C=O bonds at 180º to avoid repulsions.