Which particles make up an atom?

An atom is primarily composed of three types of subatomic particles: protons, neutrons, and electrons. Protons and neutrons are located in the nucleus at the center of the atom, giving it mass and contributing to its overall stability. Protons are positively charged, while neutrons have no charge, which helps to balance the positive charges of protons and keep the nucleus stable.

Electrons, on the other hand, are negatively charged particles that orbit the nucleus in specific energy levels or shells. The number of protons in the nucleus determines the element and its position on the periodic table, while electrons play a critical role in chemical bonding and reactions.

The other options involve combinations of incorrect particles or terms. For instance, photons are particles of light and not components of atoms. Ions refer to charged atoms or molecules, and although they result from the loss or gain of electrons, they are not fundamental particles that make up an atom. Quarks are indeed constituent particles of protons and neutrons, but they are not considered part of the structure of an atom in the same way that protons, neutrons, and electrons are when defining the atom's basic makeup.