The nucleus of an atom is made up of two types of particles: protons and neutrons. Protons are positively charged particles, while neutrons have no charge and are neutral. Together, these particles form the dense core of the atom, which is surrounded by a cloud of electrons.
Protons and neutrons are collectively known as nucleons. The number of protons in the nucleus determines the atomic number of the element, while the sum of protons and neutrons gives the atomic mass. This structure is fundamental to the properties and behavior of all matter.