What is an ion

A ion (Altgr. ion = to wander) is an electrically charged atom or molecule. A basic distinction is made between two types of ions. The positively charged ions are called cations, the negatively charged ions are called anions. Whether an ion is an anion or a cation is determined by the ratio of electrons and protons.

If an atom has more electrons than protons, then there is one Excess electrons before, and the ion is negatively charged. If an atom has fewer electrons than protons, then there is one Electron deficiency before and the ion is positively charged. If the number of electrons corresponds to the number of protons, the atom is neutrally charged and, by definition, no longer an ion.

An ion can be created from an uncharged atom by absorbing or releasing at least one electron. As already mentioned, the electron uptake leads to an excess of electrons (therefore negative charge, i.e. anion), and the release of electrons leads to a deficiency of electrons (therefore positive charge, i.e. cation).

The ion charge of an atom or molecule is usually represented as a small number in the superscript on the right. If there is only a simple excess of electrons or a lack of electrons, the number is omitted and only the charge symbol is shown.