Nuclear composition refers to the arrangement and types of particles within an atomic nucleus. The nucleus is primarily made up of two types of subatomic particles: protons and neutrons. Protons carry a positive charge, while neutrons are neutral. The number of protons in the nucleus determines the atomic number and the identity of the element. The total number of protons and neutrons in the nucleus is called the mass number. For example, a carbon atom has six protons and six neutrons, giving it a mass number of twelve. The balance between protons and neutrons affects the stability of the nucleus, influencing whether an atom is stable or radioactive.