There is a potential maximum of 50 electrons in the fifth energy level of an atom. The formula for determining the maximum number of electrons in any energy level is two times n squared, where n is the energy level.
For the fifth energy level, the formula reads two times five squared equals 50. For the first energy level, the formula is two times one squared, or two. The second energy level has two times two squared, or eight electrons. The third energy level has two times three squared, or 18 electrons. Every atom, however, does not contain the maximum number of electrons possible in its outer shell.