Atomic physics (or atom physics) is the field of physics that studies atoms as an isolated system of electrons and an atomic nucleus. It is primarily concerned with the arrangement of electrons around the nucleus and the processes by which these arrangements change.
This includes ions as well as neutral atoms and unless otherwise stated, for the purposes of this discussion it should be assumed that-the term atom includes ions.
The term atomic physics is often associated with nuclear power and nuclear bombs, due to the synonymous use of atomic and nuclear in standard English. However, physicists distinguish between atomic physics-which deals with the atom as a system of electron(s) and a nucleus-and nuclear physics-which considers atomic nuclei alone.
As with many scientific fields, strict delineation can be highly contrived and atomic often considered in the wider context of atomic, molecular and optical physics. Physics research groups are usually so classified.