Chemical stability
thermodynamic stability of a chemical system, quantitatively measured by relative molar standard Gibbs energies
Chemical stability refers to the resistance of a chemical to change in a chemical reaction. Some chemicals, like gold, are very stable and resistant to change; but sodium is unstable and corrodes rapidly in the presence of air. When an atom has an extra electron or a missing electron, it is unstable. When that atom loses or gains the electron, it becomes stable. Stable atoms have lower energy than unstable ones.