Simplest Elements:

The simplest element, hydrogen, consists of a nucleus made up of only one proton; there are generally no neutrons. This is the most ordinary element in the universe. At times a nucleus of hydrogen has a neutron or two all along with the proton, though this does not occur very frequently. These mutant forms of hydrogen do, nevertheless, play important roles in atomic physics.

The second most plentiful element in the universe is helium. Generally, this atom has a nucleus with two protons and two neutrons. The hydrogen is changed into helium inside the Sun, and in the procedure, energy is given off. This makes the Sun shine. The process, known as atomic fusion or nuclear fusion, is also responsible for the wonderful explosive force of a hydrogen bomb.