Cation
A cation is an ion with fewer electrons than protons. Therefore, it has a positive charge.
The electric charge on a proton is equal in amount to the charge on an electron. So, the total electric charge on an ion is the number of protons in the ion minus the number of electrons.
Cation Media
Hydrogen atom (center) contains a single proton and a single electron. Removal of the electron gives a cation (left), whereas the addition of an electron gives an anion (right). The hydrogen anion, with its loosely held two-electron cloud, has a larger radius than the neutral atom, which in turn is much larger than the bare proton of the cation. Hydrogen forms the only charge-+1 cation that has no electrons, but even cations that (unlike hydrogen) retain one or more electrons are still smaller than the neutral atoms or molecules from which they are derived.
Mixed Roman numerals and charge notations for the uranyl ion. The oxidation state of the metal is shown as superscripted Roman numerals, whereas the charge of the entire complex is shown by the angle symbol together with the magnitude and sign of the net charge.
An electrostatic potential map of the nitrate ion (2NO−
3). The 3-dimensional shell represents a single arbitrary isopotential.