NaCl

Stoichiometric and structure variants

Common salt has a 1:1 molar ratio of sodium and chlorine. In 2013, compounds of sodium and chloride of different stoichiometries have been discovered; five new compounds were predicted (e.g., Na₃Cl, Na₂Cl, Na₃Cl₂, NaCl₃, and NaCl₇). The existence of some of them has been experimentally confirmed at high pressures and other conditions: cubic and orthorhombic NaCl₃, two-dimensional metallic tetragonal Na₃Cl and exotic hexagonal NaCl. This indicates that compounds violating chemical intuition are possible, in simple systems under non-ambient conditions.