Britannica Sources used in this answer

Why is sodium chloride a solid at room temperature?

Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

principles of physical science Figure 1: Data in the table of the Galileo experiment. The tangent to the curve is drawn at t = 0.6.

Sodium chloride is a solid at room temperature primarily due to the strength of its ionic bonds, which result from the strong electrostatic attraction between oppositely charged sodium (Na⁺) and chlorine (Cl⁻) ions.123

In the formation of this ionic compound, ions arrange themselves into a highly stable crystalline lattice. During this process, a large amount of energy, known as lattice energy, is released. This energy release is so significant that the resulting solid state has a lower overall energy than the starting materials (sodium metal and chlorine gas), making the solid structure the most stable form at room temperature.12

Because these electrostatic forces are strong and nondirectional, the ions are held firmly in a repeating, ordered structure. Consequently, ionic solids like sodium chloride typically exhibit high melting points and remain in a solid state under standard conditions.23