Question

if atomic mass of first and third element of a triad is 6 and 18 respectively then what would be the atomic mass of the middle element according to dobereiner's triads?
- CBSE CLASS 10 BOARDS

Answer 1

According to Dobreiner's triad, the atomic mass of the central element (B) is the arithmetic mean of the atomic masses of the other two elements (A and C ).

Given that: A=7, B=15

Let the mass of C be M  

C

​  

.

M  

B

​  

=  

2

M  

A

​  

+M  

C

​  

 

​  

 

15=  

2

7+M  

c

​  

 

​  

 

⇒M  

C

​  

=23.