Atomic orbital

Atomic orbitals are the places surrounding the nucleus of an atom where the electrons are most likely to be at any given time. It is a mathematical function that describes the wave-like behavior of either one electron or a pair of electrons in an atom.

The word 'orbital' is used because it was thought that electrons behaved similarly to the solar system, where the nucleus is like the sun and the electrons orbit like the planets. 

The number of atomic orbitals in an element is defined by the period the element is in. Electrons move between orbitals depending on how much energy they have and how many other electrons there are.

In atomic theory and quantum mechanics, an atomic orbital is a quantum number. Each such orbital can be occupied by one or two electrons. The way orbitals are arranged is related to the electron configurations of atoms. They were derived from descriptions provided by early spectroscopists of certain alkali metal spectroscopic lines as being sharp, principal, diffuse, and fundamental.

Related pages
Electron cloud
Electron shell
Molecular orbital

 References 

Category:Quantum chemistry