* Ionic bonds form between metals and nonmetals. Barium (Ba) is a metal, and nitrogen (N) and oxygen (O) are nonmetals.

* Metals tend to lose electrons, forming positively charged ions (cations). Barium forms a +2 ion (Ba²⁺).

* Nonmetals tend to gain electrons, forming negatively charged ions (anions). Nitrate (NO₃⁻) is a polyatomic ion with a -1 charge.

* Electrostatic attraction: The oppositely charged ions attract each other, forming the ionic bond in barium nitrate (Ba(NO₃)₂).

Let me know if you have any other questions!