Question

Some carbon atoms have mass number 12 and some have mass number 14. These atoms of different mass numbers are called ______.

Answer 1

Isotopes: Atoms of an element having the same number of protons and electrons but different number of neutrons.

• Isotopes of Carbon are $\left({}_6{}^{12}\mathrm{C}\right)$ and $\left({}_6{}^{14}\mathrm{C}\right)$.
• These isotopes of Carbon (C) have same atomic number i.e.; 6 but have different mass number i.e.; 12 and 14.

Therefore, some carbon atoms have mass number 12 and some have mass number 14. These atoms of different mass numbers are called isotopes.