Na$_2$X ⇌  2Na$^+$  +  X$^{2-}$ The bond between Na and X is likely to be

Analyze the question: The equation shows Na₂X dissociating into 2Na⁺ and X²⁻. We are asked what type of bond holds Na and X together in the compound.

Explain the concept:

• Ionic bond: Formed by the transfer of electrons from a metal to a non-metal, producing oppositely charged ions held together by electrostatic attraction. Ionic compounds dissociate into ions when melted or dissolved in water.
• Covalent bond: Formed by the sharing of electron pairs between non-metal atoms. These compounds usually do not dissociate into ions this way.
• Dative (coordinate) bond: A covalent bond in which both shared electrons come from one atom.
• Metallic bond: Attraction between positive metal ions and a sea of delocalised electrons, found in metals and alloys.

Solution:

1. The equation shows the compound breaking into Na⁺ and X²⁻. These are charged ions.
2. Sodium is a Group 1 metal. It readily loses one electron to form Na⁺.
3. Two Na atoms lose 2 electrons in total, and X gains these 2 electrons to form X²⁻ (like S²⁻ or O²⁻). Charges balance: 2(+1) + (−2) = 0.
4. Electron transfer, which produces ions, is the hallmark of an ionic bond.
5. The fact that the compound dissociates into ions (the ⇌ equation) further supports this.

Covalent and dative bonds involve sharing, not full transfer, and metallic bonding occurs only in metals, so none of those fit.

Answer: B. ionic

Exam tip: If a formula splits into ions like Na⁺ and X²⁻, or involves a Group 1/2 metal combining with a non-metal, think ionic. Metal + non-metal = ionic; non-metal + non-metal = covalent.