Atoms are Protons, Neutrons, and Electrons, which are quarks - and there’s more.
Atoms are made up of elections, protons, and neurons, which are made up of quarks. There are 6 quarks, and it turns out there are a bunch of other tiny particles that do stuff. See the The Standard Model (Quantum Mechanics).
Basically everything other than possibly/probably gravity. Science doesn’t know.