Page "Caesium" Paragraph 16

Caesium chloride ( CsCl ) crystallizes in the simple cubic crystal system.

Also called the " caesium chloride structure ", this structural motif is composed of a primitive cubic lattice with a two-atom basis, each with an eightfold coordination ; the chloride atoms lie upon the lattice points at the edges of the cube, while the caesium atoms lie in the holes in the center of the cubes.

This structure is shared with CsBr and CsI, and many other compounds that do not contain Cs.

In contrast, most other alkaline halides adopt the sodium chloride ( NaCl ) structure.

The CsCl structure is preferred because Cs < sup >+</ sup > has an ionic radius of 174 pm and 181 pm.