The total electrical charge and the number of protons plus neutrons are conserved but the total mas is lower, and the difference in mass between the starting elements and the product elements is turned into energy according to Einstein's formula.
The 4He atom has two protons and two neutrons, plus two electrons. Thus, the total of particles after fusion is two protons, two electrons, and three neutrons. In this case, however, the helium atom and the neutron are both very, very hot.
