atomic

weight 159.2

See also:

• atomic weight 159.2 TERBIUM [symbol Tb (0=16)]

TERBIUM [

See also:

• SYMBOL (Gr. o-uµ(3oXov, a sign)

symbol Tb (0=16)]  , a metallic chemical element belonging to the rare earth group; it was originally called erbia by its discoverer Mosander (see RARE EARTH) . Pure terbium compounds were obtained by G . Urbain (Compt. rend., 1904 seq.) by fractional crystallization of the nickel double nitrates, the ethyl sulphates, and the bismuth double nitrates of the terbium earths . Terbium appears to be trivalent . The oxide is a black or brown powder according as it is prepared from the exalate or sulphate, and when pure it is non-fluorescent, but mixed with gadolinia or alumina it possesses this property . It yields colourless salts; the crystallized sulphate has the formula Tb2(SO4),.8H2O .