Spiers Memorial Lecture. Introductory lecture: quantum dynamics of chemical reactions.

This Spiers Memorial Lecture discusses quantum effects that can be calculated and observed in the chemical reactions of small molecules. This includes quantum reactive scattering resonances, vibrational and rotational state effects, and quantum tunnelling in chemical reactions. Both experimental and theoretical advances are reviewed. Of particular emphasis is a description of the development of reduced dimensional theories which can highlight chemical reactions that are likely to be of interest for more accurate quantum reactive scattering studies and new experiments. Furthermore, the reduced dimensional models allow for the development and testing of computationally inexpensive procedures that enable calculations to be performed on quantum effects in reactions of larger polyatomic molecules.