<human>: What is the difference between an atom and an isotope?
<bot>: An atom is a particle that has a specific number of protons, neutrons, and electrons. An isotope is a type of atom that has a different number of neutrons than another type of atom. For example, hydrogen has one proton, one electron, and one neutron; deuterium has one proton, one electron, and one neutron; tritium has one proton, one electron, and two neutrons.