Question

2) (A,B,C) is a Dobereiner's triad. Complete the following chart and
give reason for the answer.
Elements
A
B
С
Atomic mass
6.9
23
​

Answer 1

Answer:

if A,B,c are the Dobereiner traids then

6.9+x/2 = 23

6.9+x = 46

x = 46-6.9 =39.1

Answer 2

Answer:

C = 39

Explanation:

given:

A= 6.9

B = 23.0

C = ?

to find C,

we know that in Döbereiner's traids:

the atomic mass of the middle element was roughly the average of the atomic masses of the other 2 elements

using this here, we get

6.9+C = 23.0

2

=> 6.9 + C = 23 × 2

=> C = 46 - 6.9

=> C = 39. 1

thus , the element with atomic mass 39.1 is Potassium (K), the element with atomic mass 23 is Sodium (Na), and the element with atomic mass 6.9 is Lithium (Li).

I hope this helps you