Question

Atom A has a mass number 209 and atomic number 82.

Atom B has a mass number 209 and atomic number 83.

(i) How many protons atom A has ?

(ii) How many protons atom B has ?

(iii) Are atoms A and B isotopes of the same element ?

Answer 1

Atom A – ${}^{209}\mathrm{A}_{82}$
Atom B – ${}^{209}\mathrm{A}_{83}$

(i) A has 82 protons as the atomic number is 82.
(ii) B has 83 protons as the atomic number is 83.
(iii) No, A and B are not isotopes of each other because their atomic numbers are not same.