Trigonal

This chemistry lesson is titled VSEPR Theory Part 2 Trigonal Bipyramidal Family and will give a detailed explanation of the topic.

This video looks in detail at the nucleophilic addition reactions of ethanal and propanone with hydrogen cyanide (acidified solution of KCN actually). Cyanohydrins (hydroxynitriles) are formed. The lack of optical activity in chiral products is also explained in terms of the trigonal-planar geometry of the carbonyl.