Question

The three elements A, B and C with similar properties have atomic masses X, Y and Z respectively. The mass of Y is approximately equal to the average mass of X and Z. What is such an arrangement of elements called as? Give one example of such a set of elements.

Answer 1

Such an arrangement of elements is called triads. Example: lithium sodium and potassium make a triad. Their atomic masses are 6.9, 23.0 and 39.0 respectively. An average mass of Li and K is approximately equal to the atomic mass of Na.