Unified Atomic Mass Unit

The Unified Atomic Mass Unit (u or amu) is a standard way scientists measure the mass of atoms and subatomic particles. It is defined as one-twelfth of the mass of a carbon-12 isotope, which has six protons and six neutrons. This unit helps compare the sizes of different atoms easily. For example, a hydrogen atom's mass is close to 1 u, while a heavier element like uranium weighs several tens of u. Using this common scale allows scientists worldwide to communicate about atomic and molecular weights accurately and consistently.