 atomic 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 â which deals with the atom as a system consisting of a nucleus and electrons â and nuclear physics, which considers atomic nuclei alone. as with many scientific fields, strict delineation can be highly contrived and atomic physics is often considered in the wider context of atomic, molecular, and optical physics. physics research groups are usually so classified. ==isolated atoms== today, 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 molecules (although much of the physics is identical), nor does it examine atoms in a solid state as condensed matter. it is concerned with processes such as ionization and 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 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. ==electronic configuration== electrons form notional shells around the nucleus. these are naturally in a ground state but can be excited by the absorption of energy from light (photons), magnetic fields, or interaction with a colliding particle (typically other electrons). electrons that populate a shell are said to be in a bound state. the energy necessary to remove an electron from its shell (taking it to infinity) is called the binding energy. any quantity of energy absorbed by the electron in excess of this amount is converted to kinetic energy according to the conservation of energy. the atom is said to have undergone the process of ionization. in the event the electron absorbs a quantity of energy less than the binding e
Atomic,_molecular,_and_optical_physics Atomic_physics