amphoteric, a. rare—0.
(æmfəʊˈtɛrɪk)
[f. Gr. ἀµϕότερ-ος both, compar. of ἀµϕώ + -ic.]
Partaking of both characters; neutral, neither acid nor alkaline.
| 1849 in Smart. 1879 in Syd. Soc. Lex. |
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Delete rare—0 and for ‘neutral, neither acid nor alkaline’ read: Chiefly Chem., having or exhibiting both acidic and basic properties.
| 1906 G. Mann Chem. Proteids vi. 216 These compounds are therefore formed by the amphoteric amino-acids. 1984 Greenwood & Earnshaw Chem. of Elements (1986) vii. 253 Al(OH)3 is amphoteric, forming both salts and aluminates. 1988 Prima Aug. 36/2 L'Oreal's latest hair care range contains..amphoteric polymers which maintain the spring of the perm. |
Hence amphoˈterism n., the capacity to act as an acid or as a base.
| 1937 J. H. Yoe Chem. Princ. xvi. 164 Amphoterism and also the degree of acidic and basic ionization of amphoteric hydroxides are related to the position of their metallic elements in the periodic table. 1957 Sienko & Plane Chem. xvii. 363 Some elements, such as chromium, show amphoterism in one oxidation state but not in another. 1990 D. F. Shriver et al. Inorg. Chem. v. 161 An important issue in the d block is the oxidation number necessary for amphoterism. |