Relative isotopic mass: the mass of of one atom of an isotope compared to one twelfth of the mass of one atom of carbon-12

Relative atomic mass: the ratio of the average mass of one atom of an element to one twelfth of the mass of an atom of carbon-12.

The number of neutrons in an atom can vary which means that elements can have various isotopes
Isotopes are defined as atoms with the same number of protons but different numbers of neutrons

Relative molecular mass: The ratio of the average mass of one molecule of an element or compound to one twelfth of the mass of an atom of carbon-12

Relative formula mass: The ratio of the average mass of the formula units of a compound relative to one twelfth of the mass of an atom of carbon-12

The definitions of these terms will not be expected but please make sure you understand them.

	Created by Laura Lee about 9 years ago

Atomic Structure and The Periodic Table