Question: what is the difference between particles and atoms?

Arttu Rajantie answered on 14 Jun 2011:

In a general sense the word particle is used for any small localised object. In that sense atoms are particles. In particle physics, we use the word to mean elementary particles, which cannot be broken up into smaller pieces at least with our current technology. These are leptons, quarks, photons, gluons, W and Z bosons and the Higgs boson if it is found. In this sense atoms are not particles, because they are made of electrons and a nucleus. The nucleus consists of neutrons and protons, and these are in turn made up of quarks.