* Electron Configuration: Sodium has one valence electron in its outer shell (3s1).

* Stability: Atoms strive to have a full outer shell, which is the most stable configuration. For sodium, this means losing that one valence electron.

* Ion Formation: When sodium loses its electron, it becomes a positively charged ion (Na+), having a full outer shell like the noble gas neon.

This donation of an electron is a key factor in sodium's reactivity and its ability to form ionic bonds with other elements.