All the isotopes of an element have identical chemical properties

• All the isotopes of an element contain the same number of protons and electrons, therefore, the chemical properties of all the isotopes of an element are identical (or same).

The Physical Properties of the Isotopes of an Element are Different:

• Due to the presence of different number of neutrons, (as neutron is the heaviest particle among proton, electron and neutron) the masses of all the isotopes of an element are slightly different.
• Since the mass of the isotopes of an element are slightly different, the physical properties of the isotopes of an element are slightly different.

Radioactive isotopes:

• The isotopes which are unstable and emit various types of radiations are called radioactive isotopes.
• The radiations (such as particles, beta particles and gamma rays) are emitted by the unstable nuclei of the radioactive isotopes.
• E.g.: Carbon-14, Arsenic-74, Sodium-24, Iodine-131, Cobalt-60 and Uranium-235

Applications of radioactive isotopes:

1. Radioactive isotopes are used as a fuel in nuclear reactors of nuclear power plants for generating electricity.

• Uranium-235 isotope is used as a fuel in the reactors of nuclear power plants for generating electricity.

2. Radioactive isotopes are used as ‘tracers’ in medicine to detect the presence of tumors and blood clots, etc., in the human body.

• Arsenic-74 tracer is used to detect the presence of tumors and sodium-24 tracer is used to detect the presence of blood clots.

3. Radioactive isotopes are used to determine the activity of thyroid gland which helps in the treatment of diseases like goiter.

• Doctors used idodine-131 radioisotope as a tracer to find how and at what rate the thyroid gland in our body takes up iodine (which is essential for making thyroxine hormone). This helps in the treatment of diseases like goiter.

4. Radioactive isotopes are used in the treatment of cancer

• Cobalt–60 radioisotope is used to cure cancer.
• When the high energy gamma radiations emitted by cobalt–60 radioisotopes are directed at the cancerous tumor in the human body, the cancerous cells get burnt.
• The treatment of cancer by using radioactive radiations is called radiotherapy.

5. Radioactive isotopes are used in industry to detect the leakage in underground oil pipelines, gas pipelines and water pipes.