Proton - GCSE Physics Definition

A proton is a tiny particle found in the nucleus, or centre, of an atom, which is the basic building block of everything around us. Protons have a positive electric charge and, along with neutrons, they make up most of the mass of an atom. The number of protons in the nucleus of an atom determines which element it is. For example, all hydrogen atoms have one proton, while all carbon atoms have six protons. Protons are important because they help keep the nucleus stable.