Electron Configuration Definition

This diagram of a lithium atom
This diagram of a lithium atom indicates its electron configuration. Greg Robson, Creative Commons License

Electron configuration refers to the populations of electronic energy sublevels of an atom. The electronic configuration notations for all of the elements are available in one chart.

Example

The electronic configuration of a lithium atom is 1s22s, which indicates there are two electrons in the 1s sublevel and one electron in the 2s energy sublevel.