Question

what is the formula of the ionic compound expected to form between the elements o and ba?

Explanation:

Step1: Determine ion charges

Oxygen (O) gains 2 electrons to form $O^{2 - }$ ion as it is in group 16. Barium (Ba) loses 2 electrons to form $Ba^{2+}$ ion as it is in group 2.

Step2: Combine ions

To form a neutral ionic compound, the charges must balance. One $Ba^{2+}$ and one $O^{2 - }$ combine.

Answer:

$BaO$