What particles are primarily responsible for the mass of the atom you build?

The mass of an atom primarily comes from its protons and neutrons, which are collectively known as nucleons and reside in the nucleus. Protons carry a positive charge, while neutrons have no charge, and together they account for nearly all of an atom's mass. Electrons, which orbit the nucleus and are negatively charged, contribute very little to the overall mass of the atom due to their significantly smaller mass compared to protons and neutrons.