Atomic Weights and Isotopic Compositions for Helium
 Isotope   Relative
Atomic Mass 		    Isotopic
  Composition  		 Standard
Atomic Weight 		  Notes 
 
2 He 3     3.016 029 3201(25)   0.000 001 34(3)      4.002 602(2) g,r
4     4.002 603 254 13(6)   0.999 998 66(3)
5     5.012 057(21)   
6     6.018 885 891(57)   
7     7.027 9907(81)   
8     8.033 934 390(95)   
9     9.043 946(50)   
10   10.052 79(11)   

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