A cation is a positively charged ion formed when an atom or group of atoms loses one or more electrons. It is attracted to the negative electrode in electrochemical contexts and is typically produced by metals in groups 1 and 2 (and some transition metals) losing electrons. You can recognize and find cations on the periodic table in relation to the left-hand side where many metals reside, which tend to form cations, especially the alkali and alkaline earth metals. In compounds, cations are the positively charged partners that balance with negatively charged anions to form neutral substances. Key points

• Formation: loss of electrons by an atom or polyatomic group.
• Charge: positive; common charges include +1, +2, +3, and higher for some transition metals.
• Nomenclature: named after the parent element with the charge indicated (e.g., Na⁺ is the sodium cation; Fe³⁺ is the ferric cation).

Where to see cations on the periodic table

• Elements on the left side of the periodic table (especially Group 1 and Group 2 metals) readily form cations by losing electrons.
• The periodic table’s arrangement helps predict cation formation: elements with low ionization energies (valence electrons loosely held) tend to form cations more easily.

If you’d like, I can tailor a quick cheat sheet showing common cations and their typical charges for the most-used metals, or explain how to determine the charge of a cation from an element’s oxidation states.