The electronic configuration of an atom A is a,a+b, a+2b , a and that of B a, a + b , 3a+2b, b.
(a) Write the electronic configuration of A and B.
(b) Calculate their atomic numbers,
(c) If the number of neutrons in A is 5b and that in B is 22.5a, calculate their mass number.

Explanation

(a) The electronic configuration of A is 2, 8, 14, 2 and that of B is 2, 8, 18, 6.
(b) Their atomic numbers are 26 and 34, respectively.
(c) The number of neutrons in A is 5b= 30 and that in B = 22.5 a = 45
`therefore` Their mass numbers are 26 + 30 = 56 and 34 + 45 = 79, respectively.