What is the chemical formula for table salt?

The chemical formula for table salt is NaCl, representing sodium chloride. Each formula unit contains one sodium ion and one chloride ion in a 1:1 ratio.

Sodium chloride is an ionic compound. Sodium atoms lose an electron to become positively charged Na⁺ ions, while chlorine atoms gain an electron to become negatively charged Cl⁻ ions. The opposite charges hold the ions in a repeating crystal lattice, which is why pure sodium chloride forms brittle, often cubic crystals.

Naturally occurring sodium chloride is the mineral halite, also called rock salt. Table salt is refined edible salt and commonly contains small amounts of additives to prevent clumping; iodized salt also contains an iodine compound. Sea salt and mined salt may differ in trace minerals and processing, but their principal compound is still sodium chloride. A common mistake is writing “NaCl₂”: the charges of Na⁺ and Cl⁻ balance with one ion of each.