Crystal lattice. Computer artwork of the lattice of a body-centred cubic crystal over water. This structure is adopted by the metals lithium, sod- ium, potassium, & iron below 906 degrees Celsius. The lattice has a single atom at the centre and another eight on the corners of a cube, and it is repeated again and again to form a crystal. It is a relatively open structure, utilising about 68% of the available space. Metals that form this structure cannot use a lattice with less space because the thermal vibrations of the atoms are able to overcome the relatively weak binding forces between them.