particle

Some particle-physics terms indicating various classes of sub-atomic particles, along with their characteristics:

• spin - a quantum number indicating a type of quantum angular momentum.
• Pauli exclusion principle - a characteristic of some particles (i.e., those with half-integer spin) that two such particles are never in close association if all their quantum numbers are identical: an example is all the electrons within an atom.
• Fermi-Dirac statistics - a statistical distribution of energy levels of particles when they are in thermodynamic equilibrium if the particles are subject to the Pauli exclusion principle (as opposed to Bose-Einstein statistics).
• quantum numbers - quantum mechanical values associated with a particle or system of particles: the set of them varies by system: the total of each is conserved, i.e., changes to the particles don't change the total sums of any of the numbers. Electric charge and spin are examples. Net electric charge, for example, does not change during a particle interaction.
• strong force - one of the fundamental forces: the force that holds protons, neutrons, and atomic nuclei together.

Atomic nuclei, ions, and (neutral) atoms all fall under the category of hadron (composite particle) and can be either a fermion or boson, depending upon the constituents. Antimatter offers another dimension: some elementary particles have an associated antiparticle, e.g., a positron is an anti-electron, but both these two are leptons and fermions.