Cation

A cation is an ion with fewer electrons than protons. Therefore, it has a positive charge. Its name comes from a Greek word meaning "down".

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

• 

  Electron transfer from a neutral lithium (Li) atom on the left to a neutral fluorine (F) atom on the right would give a Li⁺ and F⁻ ions.

• 

  Schematic of an ion chamber, showing drift of ions. Electrons drift faster than positive ions due to their much smaller mass.

• 

  Avalanche effect between two electrodes. The original ionization event liberates one electron, and each subsequent collision liberates a further electron, so two electrons emerge from each collision: the ionizing electron and the liberated electron.

• 

  Equivalent notations for an iron atom (Fe) that lost two electrons, referred to as ferrous.

• 

  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.

Related pages

• Ion
• Anion