What are Isotopes: Types, Characteristics and Uses Explained

Isotopes' meaning itself suggests that they share the same chemical identity but differ in mass, giving them unique properties and uses. Have you ever wondered why some atoms of the same element are heavier than others? These atomic variations are called isotopes. This article will help you understand and define isotopes, their properties and their uses with examples. 

Table of Contents

1. What is an Isotope
2. Types of Isotopes
3. Characteristics of Isotopes
4. Applications of Isotopes
5. Difference Between Isotopes and Isobars

What is an Isotope?

The major confusion that arises is how one element exists in different forms but with little variation! That is where the Isotopes play their role. An isotope is a form of a chemical element that has the same number of protons (same atomic number) but a different number of neutrons, resulting in a different atomic mass.

In simpler terms:

All isotopes of an element behave chemically the same, but they only differ in their mass and physical properties.

Isotope Example:
Hydrogen has three isotopes:

• Protium (¹H) has 1 proton and 0 neutrons
• Deuterium (²H) has 1 proton and 1 neutron
• Tritium (³H) has 1 proton and 2 neutrons

Despite these differences in mass, all three are still hydrogen atoms.

The major thing that students might face difficulty with is in determining the Number of Neutrons in an Isotope, but you can calculate the number of neutrons in any isotope by using a simple formula:

Number of Neutrons = Mass Number – Atomic Number

 Let's understand with the example Carbon-12:

• Mass Number = 12
• Atomic Number of Carbon = 6
• Neutrons = 12 - 6 = 6

So, a Carbon-12 atom has 6 neutrons in its nucleus.

How are isotopes different from Isobars?

To know what are isotopes and isobars as Isobars, however, are like neighbours who live in houses with the same number (mass number) but have different family names (elements). 

For example, ¹⁴C and ¹⁴N weigh the same but belong to totally different families!

Also Read: Atomic Number and Mass Number 

Types of Isotopes

Interestingly, Isotopes can be categorised based on their stability and origin:

Stable Isotopes:These isotopes have nuclei that do not decay over time; that is, they remain unchanged and are not radioactive, and are considered to be stable isotopes.

Some common examples include:

• Carbon-12
• Carbon-13
• Oxygen-16 and more

• Radioactive Isotopes;Interestingly, they have unstable nuclei that decay and release radiation and play an important role in nuclear power plants, initiating a chain reaction, also used in medical imaging, cancer treatment, and carbon dating.

Common examples include:

• Carbon-14
• Hydrogen-3 (Tritium)
• Uranium-235
• Uranium-238
• Chlorine-36

Primordial Isotopes: These Isotopes have existed since the solar system was formed. The most interesting thing about them is that they have not decayed completely due to their extremely long half-lives.

Fact: Out of 339 naturally occurring isotopes, 286 are classified as primordial!

Characteristics of Isotopes

The following are some general properties of isotopes:

• They are part of the same element, hence their atomic number is the same.
• Their atomic masses vary due to a different number of neutrons.
• They exhibit similar chemical behaviour because they possess the same electron configuration.
• Physical properties, such as melting point and density, can be different for isotopes.
• Certain isotopes are stable, whereas others are radioactive and disintegrate over time.

Here are some well-known isotopes for common elements:

• Carbon: 

• Carbon-12 (¹²C) - stable

• Carbon-14 (¹⁴C) - radioactive, used in carbon dating

• Oxygen:
• Oxygen-16 (¹⁶O)
• Oxygen-17 (¹⁷O)
• Oxygen-18 (¹⁸O) – all stable
  
  
• Uranium:

Uranium-235 and Uranium-238 are used as nuclear fuel in nuclear power plants.We have already discussed the isotopes of hydrogen,like Protium, Deuterium, Tritium

Applications of Isotopes

Isotopes have widespread applications across various fields, from basic to research!

• In the Medical Field, Iodine-131 is used to diagnose and treat thyroid disorders. Radioisotopes like Cobalt-60 are used in cancer radiotherapy.
• Do you know how the isotopes serve best in Carbon-14 dating to help determine the age of ancient artefacts?
• Isotopes are also used as tracers to follow chemical pathways in plants and animals.
• Isotopes contribute a lot in power plants, especially Uranium-235 is used in nuclear reactors for power generation.

Difference Between Isotopes and Isobars

Though they sound similar, isotopes and isobars are not the same. Here's what are isotopes and isobars and how they differ:

Feature	Isotopes	Isobars
Atomic Number	Same	Different
Mass Number	Different	Same
Chemical Element	Same element	Different elements
Example	¹²C, ¹³C (carbon isotopes)	¹⁴N, ¹⁴C (different elements, same mass)

Read More: Carbon Compounds 

Isotopes are an important part of atomic structure. Define isotopes remind us that even within a single element, there's variety and depth.Understanding what are isotopes and isobars not only gives us insights into atomic science but also opens the door to real-world applications from treating illnesses to solving ancient mysteries.