* Electronegativity Difference: Magnesium (Mg) has an electronegativity of 1.31, while oxygen (O) has an electronegativity of 3.44. The difference in electronegativity is significant (2.13), indicating a strong tendency for oxygen to attract electrons.

* Electron Transfer: Magnesium readily loses its two valence electrons to achieve a stable octet. Oxygen, on the other hand, gains those two electrons to complete its octet. This electron transfer forms positively charged magnesium ions (Mg²⁺) and negatively charged oxide ions (O²⁻).

* Electrostatic Attraction: The opposite charges of the ions attract each other, forming an electrostatic bond known as an ionic bond.

Therefore, the bond between magnesium and oxygen in magnesium oxide (MgO) is primarily ionic.