cation kăt˝ī´ən [key], atom or group of atoms carrying a positive charge. The charge results because there are more protons than electrons in the cation. Cations can be formed from a metal by oxidation (see oxidation and reduction ), from a neutral base (see acids and bases ) by protonation, or from a polar compound by ionization. Cationic species include Na +, Mg ++, and NH 4 +. The cations of the transition elements have characteristic colors in water solution. Salts are made up of cations and anions . See ion .
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