Define one Atomic Mass Unit (AMU)

One atomic mass unit (a.m.u. or amu) is defined as one-twelfth (1/12) of the mass of a carbon-12 atom, which is approximately 1.660539040 × 10^-27 kilograms. It is a unit of mass used in chemistry and physics to express the mass of atoms and molecules on a scale relative to the mass of a carbon-12 atom.

Here are some key points about atomic mass units (a.m.u.) :

• Relative Mass: Atomic mass units provide a convenient scale for comparing the masses of atoms and molecules. The mass of one proton or one neutron is approximately 1 a.m.u.
• Atomic Mass: The atomic mass of an element, expressed in atomic mass units, is the weighted average of the masses of its naturally occurring isotopes, taking into account their relative abundance.
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• Molar Mass: Molar mass, measured in grams per mole, is numerically equal to the atomic mass unit and is used to convert between mass and moles in chemical calculations.

Atomic mass units are essential in chemistry for quantifying the mass of atoms and molecules, allowing scientists to work with manageable numbers when dealing with incredibly small masses at the atomic and molecular levels.