Caesium chloride 1: introduction

To go directly to the unit cell structure, click the link below to page 3.

Neither caesium chloride, nor any other mineral with this structure, is very abundant. The element caesium is the least abundant of the alkali metals (except francium, which is radioactive). It is notable (like gallium and francium) for melting at close to room temperature, when it has a gold-like lustre, and also for its use in atomic clocks which are used to define the second.

A fragment of the bulk structure of caesium chloride is shown to the left. The chloride ions are green and the caesiums are gold.

In the structure to the left the relative size of the ions is to scale, and nearest-neighbour ions are virtually in contact. In future pages the ions will not be shown in contact as it obscures the internal structure of the lattice. Rather, they will be scaled to half their atomic radius, ie one eighth of their volume. In any case, the determination of ion size has its problems. What x-ray diffraction determines most accurately are the positions of the nuclei in the lattice.

Go to page 2 to look at the structure in a different representation.

Page 2 Page 3 Page 4 Page 5