francium Chem.
(ˈfrænsɪəm)
[mod.L. (M. Perey 1946, in Jrnl. de Chim. phys. XLIII. 157), f. Franc(e: see -ium.]
A radioactive metallic element that is the heaviest member of the alkali-metal series and is chemically similar to cæsium; all its isotopes have short half-lives and only one (francium 223) occurs naturally, being produced by the radioactive decay of actinium 227. Symbol Fr; atomic number 87.
| 1946 Jrnl. & Proc. R. Inst. Chem. Dec. 277 For element 87,..the name Francium (Fr) has been suggested. 1951 J. R. Partington Gen. & Inorg. Chem. (ed. 2) xii. 323A It was at first called actinium-K but has been renamed francium (Fr.). 1963 A. G. Maddock in Mellor's Compreh. Treat. Inorg. & Theor. Chem. II. Suppl. III. ii. vi. 2516 Francium-211 may also have a half-life longer than five minutes and there is some evidence that 210Fr and 213Fr may have half-lives near one minute. Ibid. 2518 Asimov has calculated that the earth's crust contains 24·5 g. of francium. 1968 C. A. Hampel Encycl. Chem. Elem. 224/1 Francium exists in aqueous solution as a large singly-charged ion with small tendency to form complex ions. |