Answer: nS²
Answer: According to the periodic law, elements that fall into the same group have similar properties.
All the alkaline earth metals are in group two of the periodic table. The have 2 electrons in their outermost shell. In the SPDF electronic configuration the ground state of all alkaline earth have S² two electrons in their outermost S sublevel.
Example the electronic configuration of some alkaline earth metals are
Beryllium [He] 2S²
Magnesium is [Ne] 3S² and
Calcium is [Ar] 4S²
the general electronic configuration for alkaline earth metals is nS²
