Question

The atomic masses of three elements A, B and C having similar chemical

properties are 7, 23 and 39 respectively:

(a) Calculate the average atomic mass of element B according to

Dobereiner’s triads.

(b) Compare the average atomic mass of B with its atomic mass.

(c) What could the elements A, B and C be ?​

Answer 1

Answer:

(a) The average atomic mass of elements A and C =

2

7+39

=

2

46

=23

(b) The average atomic mass of elements A and C is the same as the atomic mass of element B=23.

(c) The element A is Lithium (Li), B is Sodium (Na) and C is Potassium (K). They are Dobereiner's Triads because in Dobereiner's Triads the atomic mass of the middle element is approximately the mean of the atomic masses of other two elements.

Explanation:

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