* Electronegativity Difference: Sodium (Na) is a metal with a low electronegativity, while oxygen (O) is a nonmetal with a high electronegativity. The electronegativity difference between them is large, leading to a complete transfer of electrons.

* Formation of Ions: Sodium loses one electron to become a positively charged sodium ion (Na⁺). Oxygen gains two electrons to become a negatively charged oxide ion (O²⁻).

* Electrostatic Attraction: The oppositely charged ions (Na⁺ and O²⁻) are held together by strong electrostatic forces, forming an ionic bond.

In summary, the large electronegativity difference between sodium and oxygen, resulting in the formation of ions and their subsequent electrostatic attraction, classifies Na₂O as an ionic compound.