Final answer:
Magnesium oxide (MgO) is classified as an ionic compound due to the transfer of electrons from magnesium to oxygen, resulting in the formation of Mg2+ and O2- ions, which are held together by strong electrostatic attraction.
Step-by-step explanation:
Magnesium oxide (MgO) is an ionic compound. This can be understood by examining the characteristics of the elements involved. Magnesium (Mg) has two valence electrons and a low electronegativity of 1.31, while oxygen (O) has six valence electrons and a high electronegativity of 3.44. In the formation of magnesium oxide, magnesium donates its two valence electrons to oxygen, creating a Mg2+ cation and an O2- anion. The electrostatic attraction between the positively charged magnesium ions and the negatively charged oxide ions results in the formation of a strong ionic bond. This exchange of electrons allows both magnesium and oxygen to obtain a stable octet, fulfilling the octet rule.