How small are the parts of the atom? On this page of a tutorial on particle physics, students view a diagram that shows the size of the atom in meters as it is broken down to nucleus, to proton, and finally to quark and electron. The nucleus is 10,000 times smaller than the atom. Quarks and electrons are 10,000 times smaller than the nucleus. Students read that electrons and quarks are at most ten to the negative eighteen meters in size. The site proposes to students that perhaps other smaller particles may exist that make up electrons and quarks. Copyright 2005 Eisenhower National Clearinghouse