actinide Chem.
(ˈæktɪnaɪd)
[f. actinium 2 + -ide as in lanthanide.]
One of the elements with an atomic number of 89 (actinium) or higher. Also attrib., as actinide series.
| 1945 G. T. Seaborg in Chem. & Engin. News XXIII. 2192/1 This rare-earth-like series begins with actinium in the same sense that the ‘lanthanide’ series begins with lanthanum. On this basis it might be termed the ‘actinide’ series. 1950 F. Gaynor Encycl. Atomic Energy 14 Recently the discovery of two new actinide elements, berkelium and californium has been announced. Ibid., The actinides and the rare earth elements show a striking similarity of extra-nuclear electron structure. 1958 R. D. Connor in O. R. Frisch Nucl. Handbk. iv. §21 The second ‘rare earth’ series starts at actinium and is called the actinide series just as the original series starting at lanthanum is termed the lanthanide series. |