What are the two main parts make up an atom?

Study for the Dental Radiology Foundation Chain and Physics Test. Enhance your skills with flashcards and multiple-choice questions, complete with hints and explanations. Prepare for your success!

Atoms have a small, dense center called the nucleus and a surrounding region where electrons reside. The nucleus holds protons (positive charge) and neutrons (no charge) and contains most of the atom’s mass. Electrons, which are negatively charged, form the surrounding electron cloud that balances the charge and defines the atom’s size and behavior. So the two main parts are the nucleus and the electrons around it. The other options describe subcomponents or particles that don’t constitute the two primary parts of an atom: protons and neutrons are inside the nucleus, while quarks, leptons, photons, and neutrinos are particles at a deeper level or outside the atomic structure.