Atomic physics

Atomic physics is a branch 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 consisting of a nucleus and electrons — and nuclear physics, which considers atomic nuclei alone.

History

The history of atomic physics starts with the discovery of the electron by J.J. Thomson in 1897. This discovery led to the proposal of the Plum pudding model by Thomson, which was later replaced by the Rutherford model, and then finally replaced by the Bohr model and Quantum mechanics.

Atomic Models

Plum Pudding Model

The Plum pudding model proposed by J.J. Thomson suggested that the atom was a sphere of positive charge with negatively charged electrons embedded within it.

Rutherford Model

The Rutherford model, proposed by Ernest Rutherford, suggested that the atom consisted of a tiny positively charged nucleus around which the negatively charged electrons orbited.

Bohr Model

The Bohr model, proposed by Niels Bohr, modified the Rutherford model by incorporating quantum theory. According to the Bohr model, electrons orbit the nucleus in specific, discrete energy levels.

Quantum Mechanical Model

The Quantum mechanical model of the atom is the current accepted model. It describes the electrons as existing in a cloud around the nucleus, with the cloud's density at any given point being proportional to the probability of finding the electron at that point.

Applications

Atomic physics has numerous practical applications, including in spectroscopy, quantum optics, and in developing accurate atomic clocks. It also has applications in the emerging field of quantum computing and quantum information.

See Also

• Quantum mechanics
• Quantum field theory
• Quantum electrodynamics
• Quantum chromodynamics
• Standard Model