How many energy levels will elements have if they are in Period 2? 1 2 3 4

This is what i found “nuclear fuel is material used in nuclear power stations to produce heat to power turbines. heat is created when nuclear fuel undergoes nuclear fission. most nuclear fuels contain heavy fissile actinide elements that are capable of undergoing and sustaining nuclear fission.” i hope this you for what your looking for. can you plz mark me brainliest?