Tim Cook answered
The chemical produced through the compound of Ba2 and O2 is BaO, otherwise known as Barium Oxide.
If you are working with barium oxide, keep it well sealed.
Uses for Barium Oxide
The compound is used mostly in the glass and ceramics industries, and in the production of cathode ray tubes. Barium oxide is also used in sugar beet refining, and in the manufacture of other oxides and hydroxides.
Barium oxide is toxic and an irritant, and can cause serious harm if ingested. It can be especially harmful to the eyes and skin, even in vapor form, so approach with caution.
This college professor demonstrates how to draw the Lewis structure of Barium Oxide: