All courses › Chemistry 1 › Ionic bonding

Ionic bonding

An ionic bond forms when a metal gives electrons to a non-metal. The metal becomes a positive ion, the non-metal a negative one, and opposite charges hold the crystal together. Sodium in group 1 gives away its one valence electron and gets the same electron count as neon. Chlorine in group 17 takes up one electron and gets the same count as argon. Both ions then have a full outer shell. Table salt, NaCl, is built from equal numbers of Na+ and Cl-.

Na→Na++e−\mathrm{Na} \rightarrow \mathrm{Na}^+ + e^-sodium gives away one electron
Cl+e−→Cl−\mathrm{Cl} + e^- \rightarrow \mathrm{Cl}^-chlorine takes up one electron

Symbols

NaNaatomic number 11
ClClatomic number 17

Example

Sodium has 11 electrons and is left with 11−1=1011 - 1 = 10 as Na+.

Chlorine has 17 and gets 17+1=1817 + 1 = 18 as Cl-.

Ionic compounds conduct current when melted or dissolved, because the ions can then move.
Practise chemical bonds for free →

← Noble gases · Covalent bonding →

Part of Chemistry 1: Chemical bonds.