Atoms are made up of which smaller particles?

Atoms are fundamentally composed of protons, neutrons, and electrons. Protons and neutrons reside in the nucleus at the center of the atom, contributing to its mass and stability. Protons carry a positive charge, while neutrons are neutral, providing added stability to the nucleus. Electrons, which are negatively charged, orbit the nucleus in various energy levels or shells.

This combination of protons, neutrons, and electrons determines the chemical properties of an atom, including how it interacts with other atoms to form compounds. The presence of protons defines the element itself, while neutrons can vary in number to create different isotopes of the same element. Electrons are crucial for bonding and reaction with other atoms.

The other options include particles that do not constitute the basic building blocks of atoms. For instance, ions are charged particles formed when atoms gain or lose electrons, whereas isotopes are variants of elements with differing numbers of neutrons. Photons are packets of light energy and do not form part of atomic structure. Thus, the presence of protons, neutrons, and electrons uniquely characterizes the atomic structure.