The Energy and Geometrical Structure of Molecules

Abstract

When a molecule absorbs light, it gains energy and reaches a state called an excited state. With visible or ultraviolet (UV) light, the electrons in the molecule are excited, and with infrared (IR) light, the molecular vibration is excited. When a molecule absorbs microwave, its molecular rotation is excited. This chapter seeks to explain that a molecule has discrete energy levels, by looking at three familiar examples; the color of dye molecules, the IR emission from the Earth detected by observation satellites, and microwaves arriving from space. We will also learn that we can calculate the distances among atoms within a molecule based on the scattering patterns of high energy electron beams, and that the precise geometrical structures of molecules can be determined by molecular spectroscopy and gas electron diffraction.