Type of Substance & its Particles

Depending on the type of substance, the particles in the substance can be atoms, molecules, or formula units.

For atomic substance, the particles in the substance are atoms.

*One mole of atomic substance contains 6.02 x 10²³ atoms.

Example:   1 mole of iron contains 6.02 x 10²³ Fe atoms.

For molecular substance, the particles in the substance are molecules. (Remember that a molecule is made up of 2 or more atoms.)

*One mole of molecular substance contains 6.02 x 10²³ molecules.

Example:   1 mole of water contains 6.02 x 10²³ H₂O molecules.

For ionic substance, the particles in the substance are formula units. (Remember that a formula unit is made up of a cation & an anion.)

*One mole of ionic substance contains 6.02 x 10²³ formula units.

Example: 1 mole of sodium chloride contains 6.02 x 10²³ NaCl formula units.