For example, chlorine has two isotopes (35 Cl and 37 Cl) and the relative atomic mass of chlorine is 35.5. Relative atomic masses do not have units.

It is expressed in atomic mass units (amu). For example, Carbon-12, the most common form of carbon, has an atomic mass of 12 amu, which includes 6 protons and 6 neutrons.

In a transparent medium, each photon is accompanied by an atomic mass density wave, scientists can demonstrate. The optical force of the photon sets the medium atoms in motion and makes them carry ...

The masses of both atomic nuclei and electrons influence numerous properties of atoms and molecules, for example their spectra, i.e., which light colours they absorb or emit. Physicists like values of ...