Editing Atomic physics (section)

==Isolated atoms==
Atomic physics primarily considers atoms in isolation. Atomic models will consist of a single nucleus that may be surrounded by one or more bound electrons. It is not concerned with the formation of [[molecule]]s (although much of the physics is identical), nor does it examine atoms in a [[solid-state physics|solid state]] as [[condensed matter]]. It is concerned with processes such as [[ionization]] and [[excited state|excitation]] by photons or collisions with atomic particles.

While modelling atoms in isolation may not seem realistic, if one considers atoms in a [[gas]] or [[Plasma (physics)|plasma]] then the time-scales for atom-atom interactions are huge in comparison to the atomic processes that are generally considered. This means that the individual atoms can be treated as if each were in isolation, as the vast majority of the time they are.  By this consideration, atomic physics provides the underlying theory in plasma physics and [[atmospheric physics]], even though both deal with very large numbers of atoms.