please answer

Asked by  | 28th Jan, 2009, 08:58: PM

Expert Answer:

Both groups can have dobernier triads.For example calcium (atomic weight 40), strontium (atomic weight 88), and barium (atomic weight 137) possess similar chemical prepares.  Dobereiner noticed the atomic weight of strontium fell midway between the weights of calcium and barium:
     Ca   Sr   Ba      (40 + 137) ÷ 2 = 88
      40     88     137

 Dobereiner  noticed the same pattern for the alkali metal triad (Li/Na/K) .   Li   Na  K         
      7     23     39          

Thus the triads can occur in both A and B groups.

Answered by  | 30th Jan, 2009, 03:50: AM

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