NOVA Hunting the Elements Practice Test

Solids have a definite shape and volume because their particles are tightly packed in a fixed arrangement. In the material’s examples, table salt (sodium chloride) is the solid shown. It’s an ionic compound that forms a crystal lattice, giving it a stable, rigid structure at room temperature. That crystalline, solid form distinguishes it from substances depicted as gases or vapors, like chlorine and water vapor. Sodium metal is also a solid at room temperature, but the example highlighted here is table salt, a common solid used to illustrate the solid state.