Barium, which is located in group 2 of the periodic table, is an alkaline earth metal. Atoms of barium have two electrons in their outermost shell. To achieve a more stable electron configuration, barium prefers to lose these two valence electrons rather than gain more.
When barium loses its two electrons, it forms a cation with a charge of +2. This is denoted as Ba2+. The process of losing these electrons allows barium to reach the electron configuration of the nearest noble gas, xenon, which is energetically favorable.
In summary, a barium atom wants to lose electrons, resulting in the formation of a Ba2+ ion.