The atomic mass unit (amu), also known as a unified atomic mass unit (u) or dalton (Da), is a unit of mass used to measure the mass of atoms and subatomic particles. It is defined as exactly one twelfth (1/12) of the mass of a carbon-12 atom. This means that 1 amu is equal to the mass of one carbon-12 atom divided by 12.
Key points about the atomic mass unit:
Used for atomic and subatomic particles:
The amu is particularly useful for measuring the mass of atoms and the smaller particles within them, such as protons, neutrons, and electrons.
Based on Carbon-12:
The amu is defined relative to the mass of a carbon-12 atom, making it a consistent and universally accepted standard for measuring atomic masses.
One-twelfth of Carbon-12:
One atomic mass unit is exactly one-twelfth of the mass of a single carbon-12 atom.
Approximate Value:
1 amu is approximately equal to 1.66 × 10^-27 kg or 1.66 × 10^-24 g.