4 86 



Table 599 



PERIODIC SYSTEM AND THE RADIOACTIVE ISOTOPES* 



SA 



6A 



7A 



Vb 



IVb 



Illb 



lib 



lb 



nr 



IV 

 V" 



V 

 VI 



82 



Pb 



50 



Sn 



32 



Ge 



14 



Si 



6 



C 



83 



Hi 

 Si 

 Sb 

 33 

 As 

 15 

 P 



7 

 X 



Non-metals. 



85 

 Po — 



52 



Te 



34 

 Se 

 16 



S 



53 



I 



35 



Br 



17 



CI 



o 



Inert-gases. 

 86 



Nt 



& 

 36- 

 Kr 

 18 

 Ar 

 10 

 Ne 

 2 

 He 



iA 



2A 



3A 



Light-metals. 



87 



55 

 Cs 

 37 

 Rb 

 ig 

 K 



Ra 

 56 

 Ba 

 38 

 Sr 

 20 

 Ca 



Na Mg 



Be 



Ac 

 57 

 La 

 30 

 Y 



Heavy metals. 



24 

 Cr 



23 

 V 



41 42 

 Cb Mo 



25 

 Mn 



43 



26 

 Fe 



44 

 Ru 



27 

 Co 

 45 

 Rh 



28 

 Ni 

 46 

 Pd 



29 

 Cu 



30 

 Zn 

 48 

 Cd 



31 

 Ga 

 4Q 

 In 



58 59 60 61 62 63 

 Ce Pr Nd — Sa Eu 



64 65 66 67 68 69 70 71 

 Gd Tb Dy Ho Er Ad Cp Yb 



73 

 Ta 



Bv 



74 75 



W — 



92 — 



u — 



76 77 78 



Os Ir Pt Au 



Hg 



go 

 Th 

 58 

 Ce 

 40 

 Zr 

 22 

 Ti 



Si 

 6 

 C 



32 

 Ge 



5° 



Sn 



72 

 Lu 



82 

 Pb 



SB 



6B 



7B 



3B 



VI 



Va 



IVa 

 Ilia 



Ha 



III' 



IV ' 



V 



VI 



Radioactive isotopes. 



<— Indicates the loss of an alpha particle (producing He); the element becomes more electro-positive and the atomic 

 weight decreases by 4, position changing 2 columns to the left. 



/ Indicates beta radiation (loss of electron); the element becomes more electro-negative, atomic weight remains 

 the same, position changes one column to the right and up. 



Isotopes of an element have the same valency and the same chemical properties (solubility, reactivity, etc.), al- 

 though their atomic weights may differ. The isotopes of Bi are, e.g., RaE. ThC, AcC, RaC. 



In the upper half of the table are the elements possessing high electro potential, simple spectra, colorless ions. The 

 properties are analogous in the vertical direction (groups). In the lower half are the elements with low electro-poten- 

 tial, complex spectra, colored ions and tending to form complex double salts, the general properties of the elements 

 being more pronounced in the horizontal direction (periods). 



On the left side of the table are the electro-negative elements, those of the upper half, torming strong acids, those 

 of the lower half weak oxyacids. . 



On the right si re of the table are the electro-positive elements, forming bases, oxysalts, sulfides, etc. 



The center of the lower half is occupied by the amphoteric elements forming weak acids and bases, many complex 

 compounds and double salts, manv insoluble and mostly colored compounds. 



A very striking point, however, is, as already mentioned, that the similarity amonx the elements in the upper half is 

 in the vertical direction, and in the lower half in the horizontal direction. This justifies the use of the expressions 

 group-relation and period-relation. 



* Table adapted from Hackh, J. Am. Chem. Soc. 40. i°23, 1918, Phys. Rev. 13, 169, 1910. 

 Note: See Radioactive Families with isotopes, Edna Bishop. The Physical Review, 43, 38, 1933- 



Smithsonian Tabi es. 



