Physical Properties of Caesium

Caesium is a pale-yellow metal, m.p. 28.45° C., 28.25° C., 28.2° C., 26.5° C., 26.37° C., or 26° C., b.p. 670° C., its density being 1.9029 at 0° C., 1.88 at 15° C., 1.87 at 20° C., 1.886 at 26° C., 1.836 at 27° C., and 1.827 at 40° C. The atomic volume is 71, and is higher than that of any other element. At absolute zero the density is 2.222, and the corresponding atomic volume is 59.77. The specific heat is 0.04817 between 0° and 26° C., and is given by Rengade as 0.0600 at 0° C. The heat of fusion of 1 gram is given as 3.73 cal., and also as 3.76 cal. It is the softest metal, the hardness on Rydberg's scale being 0.2. Neither the metal nor any of its salts displays radioactivity.