Electron shell

An electron shell (or atomic shell) is the region of space around an atom in which an electron with a particular amount of energy can reside. Electron shells are denoted using principle atomic numbers n=1, 2, 3, 4, 5, 6, 7 with each higher number indicating a higher energy region and are further away from the nucleus. Each shell can hold 2n² electrons. The outer part of the atomic shells, the Valence shell, is responsible for the chemical bonds in particular.

The subdivision of Atoms in atomic nucleus and atomic shells goes back to the Geiger–Marsden experiment.

See also

• Electron subshell
• Orbital