Isotopes

The atomic number is a fundamental property of an element and determines its chemical identity. However, some elements in nature have atoms with the same atomic number but different mass numbers. These atoms of the same element with different mass numbers are called isotopes. Therefore, we can say that there are three isotopes of a hydrogen atom, namely protium, deuterium, and tritium.

The isotopes of an element have the same proton number but different neutron numbers.

Isobars

It can be defined as the atoms of different elements with different atomic numbers, which

have the same mass number. Example – calcium, atomic number 20, and argon, atomic

number 18. The number of protons in these atoms is different, but the mass number of

both these elements is 40

Some isotopes are radioactive and are used in various fields such as industry, agriculture, medicine, and research.

1. Uranium-235 is used for nuclear fission and the production of electricity.
2. Cobalt-60 is used in the medical treatment of fatal diseases like cancer.
3. Iodine-131 is used for treating goitre, a disease of the thyroid gland.
4. Sodium-24 is used to detect cracks and leakage in underground pipes.
5. Radioactive isotopes are used to preserve food from microbial contamination.
6. Carbon-14 is used for determining the age of archaeological objects.

The atoms of the same element, having same atomic number Z, but different mass number A, are called isotopes.

OR

Atoms having the same atomic number (Z) but different mass numbers (A).