Human: What are some of the most interesting facts about the atom? Assistant: 

1. The atom is the smallest unit of matter that still has the properties of a chemical element.
2. Atoms are made up of protons, neutrons and electrons.
3. Protons and neutrons are composed of three quarks bound together by gluons.
4. Atoms have different isotopes which are atoms with the same number of protons but different numbers of neutrons.
5. An atom’s nucleus contains protons and neutrons held together by electromagnetic forces.
6. Electrons orbit around the nucleus in shells.
7. The electron cloud surrounding an atom can be thought of as the atom's "outer shell."