Answer:
Subatomic particles making up an atom
Step-by-step explanation:
Atom is the smallest unit of any matter
An atom consists of three subatomic particles - Protons, Neutrons, Electrons. Major atomic mass is in the nucleus ie a tiny deep area at the centre. Nucleus consists nucleons, which includes protons (positively charge) & neurons (neutrally charged). Negatively charged electrons are outside the central nucleus.