Table 628 

 THORIUM FAMILY: POTASSIUM, RUBIDIUM 



519 



Rays and 

 end product 



Thorium 



Mesothor- 

 ium 1 



Mesothor- 

 ium 2 



Radiothorium 



Thorium X 

 Thoron 

 Thorium A 

 Thorium B 

 Thorium C 



Thorium C 



65% 



65-7% 

 Thorium C" 



35% 



34-3% 

 Thorium D 

 Thorium lead 



Pb2o8 



Th 



At. Wt. 232.12 



At. No. 90 



P. No. 232 



MsTh, 



At. No. 88 



P. No. 228 



MsTh 2 



At. No. 89 



P. No. 228 



RdTh 



At. No. 90 



P. No. 228 



ThX 



At. No. 88 



P. No. 224 



Tn 



At. No. 86 



P. No. 220 



ThA 



At. No. 84 



P. No. 216 



ThB 



At. No. 82 



P. No. 212 



ThC 



At. No. 83 



P. No. 212 



ThC 



At. No. 84 



P. No. 212 



ThC" 



At. No. 8r 



P. No. 208 



ThD 



At. Wt. 208.016 



(?) 

 At. No. 82 

 P. No. 208 



i.8-io 10 yr 

 5.6io n s 



6.7yr 

 2.1 -io 8 s 



6.i3h 



2.2II0 4 S 



i -90yr 

 6.oio 7 s 



3.64d 

 3.i4io 5 s 



54-5S 



0.14s 



10. 6h 

 3.82- 1 o 4 s 



60.5m 

 3.63 io 3 s 



io- 9 s(?) 



< IO" 6 S 



3.1m 



1 86s 



4.oio- 11 yr- 1 



o.i03yr 1 

 3.26io- 9 s- 1 



o.U3h 1 

 3.i4-io- 6 s- 1 



o^syr 1 

 i.i6io- 8 s- 1 



o.i9od ' 



2.20-I0" 6 S- 1 



I.27-IO" 2 S- 



4-95S" 1 



6.54-io- 2 h-' 



I.82IO- 6 S" 1 



i.iS-io^rrr 1 

 i.gi-io-V 1 



io 9 s-'(?) 

 > ioV 1 



2.24-io 1 m- 1 

 3.73-io- 3 s 1 



2.5-io 10 yr 

 8.o-io 17 s 



7yr 

 05 • 1 o 8 s 



84h 

 i8-io 4 s 



74y 



65io 7 s 



25d 

 54-io 5 s 



78.7s 



i5-3h 

 5.51 -io 4 s 



87.3m 

 5.24- io 3 s 



io- 9 s(?) 



< IO" 6 S 



4.47m 

 286.3s 



a, MsThi 



/3, MsTh 2 



j8, RdTh 



a, ThX 



a, Tn 



a, ThA 



a, ThB 



j8, ThC 



18, a, .65ThC 

 •35ThC" 



a, ThD 



B, ThD 



Potassium (K19) and rubidium (RD37) emit B rays; the B-ray activity of rubidium 

 is 1/15 that of uranium; T is about io 11 years. Cesium (55Ce) has been found to have 

 an activity less than 1/90 of potassium. Hoffman considers neither sodium nor 

 cesium radioactive. Be, av. period io 14 years, (Langer, Raitt, 1933). 



Note — The following data is from Holmes, Lawson, Nature, 117, 620, 1926: 



Ur 



Th 



Rb 



N, atoms per g 



T, half-value period, years 

 X, disintegration constant, 



years -1 



No. atoms disintegrating 



per years, n\ 



Kinetic energy, E ergs per 



S ray 



Energy per g, per year, 



nE/(\. 19 X io 7 ) cal. . . . 



(7900 X 10- 



(2300 X io 4 ) 



15-5 X io 21 

 15 X io 11 



4.6 X io i; 



7.1 X io 9 



7.30 X 10- 7 



1.24 X 10- 4 



7.09 X io 21 

 1 X io 11 



69 X io i: 



49 X io 9 



2.04 X 10- 7 



2.38 X 10- 4 



Smithsonian Tables 



