Atomic Mass Units (amu)

Definition

Atomic mass units, or amu, is a standard unit of mass that quantifies mass on an atomic or molecular scale. One amu is approximately equal to the mass of one proton or neutron.

Related terms

Proton:

A subatomic particle carrying a positive electric charge, found in the nucleus of an atom. Its mass is roughly equivalent to 1 amu.

Neutron: A subatomic particle found in the nucleus of an atom. It carries no electrical charge and its mass is also roughly equivalent to 1 amu.

Electron:

A subatomic particle carrying a negative electric charge. It's much lighter than protons and neutrons with a relative mass close to 0 amu.