1. Tardigrade
  2. Question
  3. Chemistry
  4. Atomic mass of Cl =35.5 u and that of I =127 u. According to Dobereiner's triad rule, atomic mass of Br will be u.

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Q. Atomic mass of $Cl =35.5\, u$ and that of $I =127\, u$. According to Dobereiner's triad rule, atomic mass of $Br$ will be____ $u$.

Classification of Elements and Periodicity in Properties

Solution:

According to Dobereiner, the middle element has an atomic mass almost the average of the other two elements.
Hence, $\frac{35.5+127}{2}=81.25\, u$