Alkali metal

Alkali metals are a group of soft, white, highly reactive metallic elements, including lithium, sodium, potassium, rubidium, caesium, and francium. Low typical ionization energies give these elements their metallic behavior and high reactivities.

Ionic states

Occupying the left-most column of the periodic table, alkali atoms have a single valence electron and are readily ionized by its removal, resulting in an ionic charge of +1. Subsequent ionization to more highly charged states requires considerably more energy, as singly-ionized alkali atoms have a noble-gas configuration of electrons (I.e., the outer shell of electrons is completely filled.)