What Are Positive And Negative Ions?

An ion is an atom, or a group of atoms, which has an electrical charge. This charge can be either positive or negative, and this will determine what type of ion it is.

The electrical charge of the ion depends on the number of electrons in its electron shells. A positive ion (also know as a cation) possesses one fewer electrons in its electron shells than it does protons in its nuclei. The number of shells is dependent upon the size of the atom. Conversely, a negative ion will have one more electron than it will protons.

Michael Faraday was the first to define ions, when he used the term to describe the parts of molecules that traveled either to anodes or cathodes. The term is derived from the Greek for 'to go'. Ions are everywhere around us, and are vital for life ~ we could not survive, for example, without sodium, potassium and calcium ions. Ions have also found other uses in practical applications such as smoke detectors and air purifiers.

In an atom, the number of protons is the same as the number of electrons. The atom is electrically neutral. If electrons are added to or taken away from an atom, then the atom is no longer electrically neutral. It becomes a charged particle, which is called an ion.