Question

What is the difference between an isotope and a radioisotope?

Answer 1

Atoms are the smallest building blocks of all substances. There are several types of atoms present around us. Atoms of the same element can be different due to the difference in the number of nucleons of the atoms. These atoms are known as isotopes. When the nucleus of any such isotopes becomes unstable, they become radioactive in nature.

Complete answer:
An isotope is a variant of an element in different forms of atoms that contain the same number of electrons and protons but differ in the number of neutrons. For example: carbon-12, carbon-13, and carbon-14 are all isotopes of carbon. They all only differ in the number of neutrons as shown below:
Isotopes have similar atomic numbers but different atomic masses. The British physicist J.J.Thomson was the first person to find evidence for isotopes of the element neon in 1912. Later on, some other scientists started discovering several other stable isotopes of elements using a mass spectrograph.
Few isotopes were found to have heavy unstable nuclei and they tend to disintegrate into comparatively lighter stable particles by emission in the form of radiation. Such unstable isotopes of an element that shows radioactivity are known as radioisotopes.
Hence, major differences between an isotope and a radioisotope are:
1 – Radioisotopes show radioactivity while isotopes do not, and
2 – Isotopes are somewhat stable while radioisotopes are very unstable.

Note:
In a normal atom, the nucleus is stable. However, in the nuclei of radioactive elements, there is an unstable combination of neutrons and protons and thus they are not stable. To become stable, these nuclei emit particles, and this process is known as radioactive decay. For example, Uranium has two isotopes as U-235 and U-238. From these two, U-238 is stable, but the U-235 isotope is radioactive and is used in atomic bombs and nuclear fission reactors.