Atom

An atom is a particle that makes up most of Universes alongside Dark Matter, relative to the Multiverse of which humans live in. They are also the biggest particle of which quantum affects apply.

Like Molecules, they can enter various states of matter, with each hotter one leading to a more chaotic outcome. Solids are more fixed, liquids can fluidly move around, gases are less bound by gravity, and plasmas no longer have Electrons bound to an atom's nucleus.

However, their properties are mainly determined by the number of Protons in the nucleus, which determines the atomic number. This leads to an Atom being a different element, such as Hydrogen or Lithium or Uranium. Currently, 118 elements are known, although more may be discovered by humans in the future.

Other particles' affects on Atoms
Neutrons can affect the stability/half-life of an Atom (as well as isotope), and Electrons mainly define how atoms bind into molecules. This is explained in more detail on the Molecule page.