If something is smaller than an atom, does it always mean that the atom is made up of that thing ..?

Answer 1

Hello!

An atom is just a general composition of all matter in the universe. No matter what you come in contact with, that material comprises millions of atoms. Now in the atom contains much smaller particles (sub-particles), such as electrons, neutrons, and protons. And even beyond that, there are much smaller particles (sub-sub-particles) such as positrons, bosons, quarks. Every atom can be made up of these smaller particles, so you can conclude that if the particle is smaller than an atom and is contained within that atom, then yes, that atom is made up of those particles.