Isotopes

Isotopes are those atoms that are having the same atomic number or the same position in the modern periodic table but with different atomic masses. This difference in atomic mass arises from the different numbers of neutrons present in the nucleus of the atom. As they lie in the same position on the periodic table they almost have similar chemical properties but different physical properties due to the difference in atomic mass. Other than Isotopes, there are isobars, and isotones are also defined based on the number of subatomic particles in the atom.

Isotopes Definition

Isotopes are variations of the same element with a different number of nucleons. In other words, nuclei with the same number of protons and different numbers of neutrons are classified as isotopes. For example, all carbon atoms contain six protons, but some have 6, 7, or 8 neutrons in the nucleus, which classify these carbon atoms as C-12, C-13, and C-14.

There are several isotopes found in nature in the stable form but some are found in the unstable form(radioactive). The most stable and common isotopes of an element are often one or two of them. Due to their similar proton and electron numbers, different isotopes of an element usually share the same physical and chemical characteristics.

Examples of Isotopes

There are a lot of examples of the nature of Isotopes, some of which are as follows:

Isotopes of Hydrogen

Hydrogen has three naturally occurring Isotopes. Isotopes of Hydrogen are ₁H¹ Protium, ₁H² Deuterium, and ₁H³ Tritium, but in a lab environment, we can create more isotopes with different numbers of neutrons in the nuclei of it. These synthetic isotopes of Hydrogens are all radioactive and have a half-life of the order of yotta seconds.

 

Isotopes of Carbon

Carbon-13 and Carbon-14 are both isotopes of carbon, one with 7 neutrons and one with 8 neutrons (but both with 6 protons). Carbon-12 is a stable isotope, while carbon-14 is a radioactive isotope (radioisotope). Other than this, many synthetic carbon isotopes are synthesized in a lab environment and can only sustain for a very brief period of time(order of 200 ms).

 

Isotopes of Oxygen

There are only three stable isotopes of oxygen which are ¹⁶O, ¹⁷O, and ¹⁸O. Other than this oxygen nuclei with a different number of neutrons such as 3, 4, 5, 6, 7, etc. can be synthesized in labs but they are not stable in nature and only can exist in the lab environment. 

Learn More,

• Why do all the Isotopes of an Element have similar Chemical Properties?
• Why do Isotopes have different Physical Properties?
• What is Fractional Atomic Mass?

Types of Isotopes

There are two types of Isotopes based on their stability, stable and unstable (radioactive) isotopes, which are explained as follows:

• Stable Isotopes
• Radioactive Isotopes
• Primordial Isotopes

Now let’s learn about them in detail.

Stable Isotopes

Stable isotopes are isotopes with extraordinarily long half-lives (half-life is defined as the time it takes for a substance to decompose and reach a concentration or weight that is half, or 50%, of its initial concentration or weight). Examples of Stable Isotopes are Carbon (Carbon-12, Carbon-13, and Oxygen (Oxygen-16, Oxygen-17, and Oxygen-18).

Radioactive Isotopes

Some isotopes have extremely short half-lives and degrade quickly, emitting radioactive waves as they do so. These are known as radioactive isotopes. Isotopes that are radioactive include Tritium, Carbon-14, etc.

Primordial Isotopes

The nuclides that have been around since the creation of our solar system are known as primordial nuclides. On Earth, there are 339 naturally occurring isotopes in total, 286 of which are Primordial Isotopes.

What are Radioactive Isotopes?

Radioactive Isotopes aka Radioisotopes, are unstable isotopes of an element. These isotopes emit radiation in the form of radioactive decay. Most radioisotopes are created through nuclear reactions, such as those that occur in nuclear reactors or particle accelerators. But some radioisotopes occur in nature such as carbon-14 and uranium-238. These isotopes go through the process of radioactive decay to form more stable nuclei and emit alpha, beta and gamma radiation during the decay. These emissions of radiation took place over a very short period of time or over millions of years, depending on the half-life of the isotope.

Isotopes of Uranium

Uranium is a naturally occurring radioactive element found in nature that has many isotopes but no isotope is stable in nature. But some of these radioactive isotopes have a significant half-life (in order of million years). Also, it has two primordial isotopes i.e., U-235 and U-238, out of which U-238 is the most abundant isotope on earth and has the most half-life as well. Therefore it is used in research and nuclear applications.

Application of Radioactive Isotopes

The following are the important uses of Radioactive Isotopes:

• Radioactive Dating: Radiocarbon dating, which determines the age of carbon-bearing objects, uses the radioactive isotope carbon-14. Because radioactive isotopes’ half-lives are unaffected by external variables, the isotope functions as an internal clock.
• Irradiation of Food: Some radioactive compounds produce radiation that may be used to destroy germs on a range of goods, therefore prolonging their shelf life. Tomatoes, mushrooms, sprouts, and berries are all irradiated with cobalt-60 or cesium-137 emissions.
• Medical Applications: Radioactive isotopes offer a wide range of medicinal uses, including the diagnosis and treatment of sickness and disease. For example, ³²P is utilized for cancer identification and therapy, particularly in the eyes and skin, ⁵⁹Fe for anaemia diagnosis, ⁶⁰Co for tumor gamma-ray irradiation, ¹³¹I for thyroid function diagnosis and treatment, and many more uses.
• Other uses: Radioactive isotopes find uses in agriculture, the food industry, pest control, archaeology, and medicine. 

Uses of Isotopes

Some of the important uses or applications of Isotopes are:

• Isotopes are used in various industrial applications, like detecting leaks in pipelines and testing the integrity of materials for various use cases.
• Different Isotopes of Uranium and Plutonium are used in nuclear reactors to make nuclear energy.
• Isotopes provide particular elements with the same atomic number and particular properties. As a result, isotopes are employed in the element’s chemical analysis.
• Due to their ease of measurement, isotopes are frequently employed to gauge reaction rates or changes in the concentration of reactants and products.
• Additionally, they are employed in analytical processes like nuclear magnetic resonance and mass spectrometry.

Differences between Isotopes and Isobars

There are several differences between Isotopes and Isobars, which are as follows:

Read More,

• Atomic Structure
• Radioactive Elements
• Atoms and Molecules

Sample Question on Isotopes

Question 1: What are the Applications of Isotopes?

Answer: 

Various examples of the isotopes are,

• Isotopes provide particular elements with the same atomic number and particular properties. As a result, isotopes are employed in the element’s chemical analysis.
• Due to their ease of measurement, isotopes are frequently employed to gauge reaction rates or changes in the concentration of reactants and products.
• Additionally, they are employed in analytical processes like nuclear magnetic resonance and mass spectrometry.

Question 2: Isotopes have the same chemical properties while isobars do not have the same. Why?

Answer: 

Isotopes of an element have the same number of electrons and protons but have different numbers of neutrons. Since the chemical properties of elements depend upon the atomic number, isotopes of an element have simile chemical properties.

On the other hand, isobars have different numbers of electrons, protons as well as neutrons. Thus, isobars have different chemical properties.

FAQs on Isotopes

What are Isotopes?

Isotopes are those elements in which the number of protons in an atom of a given element is constant, while the number of neutrons might vary. 

For example, C-12, C-13, and C-14 are examples of isotopes of carbon, where all of them have six protons but six, seven, and eight neutrons, respectively.

What are Isotopes of Hydrogen?

Hydrogen has three naturally occurring Isotopes. Isotopes of Hydrogen are ₁H¹ Protium, ₁H² Deuterium, and ₁H³ Tritium.

Which Isotope of Hydrogen is Radioactive?

There are three isotopes of hydrogen, of which the third, Tritium (₁H³), is the radioactive one.

Who is Credited for the Discovery of Isotopes?

The radiochemist Frederick Soddy was the first person to suggest the existence of isotopes in 1913.

Which Radioactive Isotope is used in Treatment of Cancer?

Cobalt-60 is the most commonly used radioactive isotope in the treatment of cancer.