* One magnesium ion (Mg²⁺)

* One oxide ion (O²⁻)

Let me explain:

* Magnesium (Mg) is a metal that readily loses two electrons to form a positively charged ion, Mg²⁺.

* Oxygen (O) is a nonmetal that readily gains two electrons to form a negatively charged ion, O²⁻.

These oppositely charged ions attract each other, forming an ionic bond and creating the compound MgO.