What subatomic particles make up an atom?

Atoms are primarily composed of three types of subatomic particles: protons, neutrons, and electrons. Protons are positively charged particles found in the nucleus of an atom, while neutrons, which have no charge, also reside in the nucleus and help to stabilize it. Electrons, carrying a negative charge, orbit the nucleus in defined energy levels or shells.

This combination of protons and neutrons in the nucleus determines the atomic number and mass of the element, while the arrangement of electrons around the nucleus plays a crucial role in chemical bonding and reactions. Understanding these three particles provides a foundational knowledge of atomic structure and chemistry as a whole. Other choices mention particles that do not accurately complete the atom's standard composition or include incorrect groupings. For example, positrons are the antiparticles of electrons, ions are atoms or molecules that have a net electric charge due to the loss or gain of electrons, and quarks are fundamental components of protons and neutrons, not standalone components of atoms.