Autoionization is a process by which atoms or molecules spontaneously transition from an electrically neutral state to a lower-energy ionized state. Properties For alternative meanings see atom (disambiguation). ... In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ... A spontaneous process in chemical reaction terms is one which occurs with the system releasing free energy in some form (often, but not always, heat) and moving to a lower energy, hence more thermodynamically stable, state. ... ...

Atoms can autoionize when the two outer electrons are both excited and, through electrostatic interactions, one of the electrons is ejected, ionizing the atom. Properties The electron (also called negatron, commonly represented as e−) is a subatomic particle. ... Excitation is the amount of energy (energy in a general sense, not energy as defined in physics) that something or someone has. ... Electrostatics is the branch of physics that deals with the force exerted by a static (i. ...

For an example of molecular autoionization, see Self-ionization of water. The self-ionization of water is the chemical reaction in which two water molecules react to produce a hydronium (H3O+) and a hydroxide ion (OH-): The reaction is also known as the autoionization or autodissociation of water. ...

Other examples are given by the autoionization of core-excited molecules, see Auger effect, or of Rydberg atoms. The Auger effect is a phenomenon in physics in which two electrons are emitted from an atom. ... A Rydberg atom is an excited atom with one or more electrons that have a very high principal quantum number. ...

Autoionizing states are resonances. In physics, resonance is the tendency of a system to absorb more oscillatory energy when the frequency of the oscillations matches the systems natural frequency of vibration (its resonant frequency) than it does at other frequencies. ...

More specifically, autoionization refers to non-redox ionization of a molecular substance. See molecular autoionization Molecular autoionization is a reaction between molecules of the same substance to produce ions. ...

See also

• resonance