Answers

2016-05-04T16:14:39+05:30
He grouped the elements in triads in such a way that the middle element of the triad had both atomic mass and properties roughly equal to the average of other two elements of the triad.
EXAMPLES :-
1) Ca(40), Sr(88), Ba(137) : (40+137)÷2=88.5
2) Li(7), Na(23), K(39) : (7+39)÷2=23.
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