* Ionic compounds are formed by the electrostatic attraction between positively charged ions (cations) and negatively charged ions (anions).

* Sodium (Na) is a metal and tends to lose one electron to form a positively charged sodium ion (Na⁺).

* Oxalate (C₂O₄²⁻) is a polyatomic ion with a negative charge. It's formed from two carbon atoms and four oxygen atoms.

In sodium oxalate, two sodium ions (Na⁺) bond with one oxalate ion (C₂O₄²⁻), forming a neutral compound. The strong electrostatic attraction between the oppositely charged ions is what defines the ionic nature of the compound.