ATOMIC STRUCTURE VOCABULARY WORD Definition ATOM The smallest particle of an element that keeps the properties of that element ELEMENT A pure substance made of only one type of atom MOLECULE The smallest particle of a compound that keeps the properties of that compound COMPOUND A pure substance made of only one type of molecule; particles are atoms bonded together – molecules PROTON One of the particles found in the nucleus of an atom; contains a positive charge NEUTRON One of the particles found in the nucleus of an atom; contains a neutral charge (no charge) ELECTRON One of the three particles that make up an atom; found in the area surrounding the nucleus of the atom; has a negative charge NUCLEUS The center of an atom; consists of protons and neutrons held together by a strong force; accounts for the mass of the atom ELECTRON CLOUD Term used to describe the area where the electrons are located outside the nucleus of an atom ATOMIC MASS UNIT The value used to describe the mass of a proton or a neutron ATOMIC STRUCTURE VOCABULARY