A solvated electron is a free electron in (solvated in) a solution, and is the least possible anion. Solvated electrons happen widely although they are often not practical directly. The deep color of solutions of alkali metals in ammonia rises from the presence of solvated electrons: blue when dilute and copper-colored when more concentrated (> 3 molar). Naturally, discussions of solvated electrons focus on their solutions in ammonia, which are stable for many days, but solvated electrons happen in water and other solvents, in fact, any solvent that mediates outer-sphere electron transmit. The solvated electron is dependable for a great deal of radiation chemistry.