Atoms or molecules become ions by the gain or loss of electrons, which have a negative charge. A positively charged ion, or cation, involves a loss of one or more electron(s). A negatively charged ion, or anion, involves a gain of one or more electron(s).

See cation exchange.

A fluxional bond formed between an ion and a polar molecule. The classic example is where water molecules hydrate a sodium cation. However, the interaction is not restricted to H₂O, as many polar organic molecules will form ion-dipole interactions.
See fluxional bond.

the ratio (I_p) of charge (z) on an ion to the radius (r) of the ion, I_P = z/r.

The ratio (I_p) of charge (z) on an ion to the radius (r) of the ion, I_P = z/r.

An obsolete, local term for a kaolin forming crusts in the Ione sandstone, California, USA.

See hydrotalcite group.

An obsolete term for annite, siderophyllite, biotite, and hematite.

An invalid name for a hypothetical end member.

An obsolete varietal term for ferrian illite.