Answer to Question #109837 in General Chemistry for Ambika priyadarsini

Question

How many normal modes of vibration are possible for a (5)
(i) linear molecule, and
(ii) Non-linear molecule?

Answer 1

In general, a non-linear molecule with N atoms has 3N – 6 normal modes of vibration, but a linear molecule has 3N – 5 modes, because rotation about the molecular axis cannot be observed.