In chemistry, a zwitterion (/?tsv?t?r.a?.?n/ tsvit-?r-eye-?n; from German zwitter ?tsv?t? "hybrid" and formerly called a dipolar ion) is a neutral molecule with both a positive and a negative electrical charge. Multiple positive and negative charges can be present. Zwitterions are distinct from dipoles, at different locations within that molecule. Zwitterions are sometimes also called inner salts.
Unlike simple amphoteric compounds that might only form either a cationic or anionic species depending on external conditions, a zwitterion simultaneously has both ionic states in the same molecule. Wikipedia, Zwitterion
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