Compounds

Compound

A substance that contains combined elements in fixed, definite proportions.

Chemical formula

A representation of a compound that indicates the proportions of different atoms in the compound.

Subscript

A number written below and to the right of an element's symbol in a chemical formula, indicating the number of atoms of that element in a molecule.

Metallic elements

Elements that exhibit properties of metals, typically found on the left side of the periodic table.

Cations

Positively charged ions, often formed by the loss of electrons from metallic elements.

Anions

Negatively charged ions, typically formed by the gain of electrons by nonmetallic elements.

Ionic compounds

Compounds composed of cations paired with anions, formed through the transfer of electrons.

Molecular compounds

Compounds composed of two or more nonmetals, formed through the sharing of electrons.

Charge

The electrical charge of an ion, either positive (for cations) or negative (for anions).

Subscript change

If the subscript of an element in a chemical formula changes, the formula represents a different compound.