Define: ion

define: polar molecule

define: subscript

define: coefficient

Ion - an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

Polar molecule - A polar molecule is a molecule containing polar bonds where the sum of all the bond's dipole moments is not zero.

Subscript - A subscript is a character, usually a letter or number, that's printed slightly below and to the side of another character.

Coefficient - a coefficient is a constant term related to the properties of a product.