Atomic physics

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.

These are normally 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 ions or other electrons).

In this case, a visible photon or a characteristic X-ray is emitted, or a phenomenon known as the Auger effect may take place, where the released energy is transferred to another bound electron, causing it to go into the continuum.

It introduced the idea of quantized orbits for electrons, combining classical and quantum physics.

This theory was later developed in the modern sense of the basic unit of a chemical element by the British chemist and physicist John Dalton in the 18th century.

The invention of the periodic system of elements by Dmitri Mendeleev was another great step forward.

The true beginning of atomic physics is marked by the discovery of spectral lines and attempts to describe the phenomenon, most notably by Joseph von Fraunhofer.

The study of these lines led to the Bohr atom model and to the birth of quantum mechanics.

This can be attributed to progress in computing technology, which has allowed larger and more sophisticated models of atomic structure and associated collision processes.

[3][4] Similar technological advances in accelerators, detectors, magnetic field generation and lasers have greatly assisted experimental work.

Beyond the well-known phenomena which can be describe with regular quantum mechanics chaotic processes[5] can occur which need different descriptions.