| 单词 | zwitterion |
| 释义 | zwitterion(ampholyte ion) An ion that has a positive and negative charge on the same group of atoms. Zwitterions can be formed from compounds that contain both acid groups and basic groups in their molecules. For example, aminoethanoic acid (the amino acid glycine) has the formula H2N.CH2.COOH. However, under neutral conditions, it exists in the different form of the zwitterion +H3N.CH2.COO-, which can be regarded as having been produced by an internal neutralization reaction (transfer of a proton from the carboxyl group to the amino group). Aminoethanoic acid, as a consequence, has some properties characteristic of ionic compounds; e.g. a high melting point and solubility in water. In acid solutions, the positive ion +H3NCH2COOH is formed. In basic solutions, the negative ion H2NCH2COO- predominates. The name comes from the German zwei, two. |
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