Physics Wallah

Understanding Isotopes, Isobars, and Isotones

Isotopes, isobars, and isotones are three fundamental concepts that shed light on how atoms differ and how they influence the behaviour of matter in the world of science and chemistry.
authorImageRanvijay Singh28 Oct, 2023
Share

Share

Isotopes, Isobars, and Isotones

Isotopes, Isobars, and Isotones are fundamental concepts in nuclear physics and chemistry. They help us understand the diversity of atomic structures and the various ways in which atoms can differ from one another. Let's delve into these terms to gain a better grasp of their definitions and examples.

Define Isotopes, Isobars, and Isotones

  • Isotopes - Atoms of the same element with the same number of protons but different numbers of neutrons are called isotopes. Depending on the number of neutrons in the atom, atomic masses can differ. For example, carbon has two stable isotopes, carbon-12 and carbon-13, each with 6 and 7 neutrons.
  • Isobars - Isobars are atoms of different elements with the same mass number, meaning they have the same number of protons and neutrons. They may have different atomic numbers, indicating they are distinct elements. Examples are calcium-40 (20 protons and 20 neutrons) and argon-40 (18 protons and 22 neutrons).
  • Isotones - Isotones are atoms with the same number of neutrons but different atomic numbers and, consequently, different chemical elements. An example is carbon-14 and nitrogen-14, both having 7 neutrons but different numbers of protons, 6 for carbon and 7 for nitrogen.

What are Isotopes?

Isotopes are different versions of an element, distinguished by the number of neutrons they contain. For instance, consider Uranium isotopes 23592 U and 23992 U. While they have the same number of protons, their neutron counts differ, with 143 for the former and 147 for the latter. This additional neutron dramatically alters the properties of the atom. Isotopes can be classified as stable or radioactive. Stable isotopes remain intact without any spontaneous disintegration. At the same time, radioactive isotopes are too unstable to sustain themselves and eventually break down into lighter elements through the emission of particles like alpha, beta, and gamma rays.

What are Isobars?

A series of elements with 40 mass numbers serves as a good example of an isobar; 4016 S, 4017 Cl, 4018 Ar, 4019 K, and 4020 Ca. are all elements with the same number of nucleons (protons and neutrons). There are the same number of particles in the nucleus of all of the above-mentioned elements, but their protons and neutrons vary in number.

Also Read – Malic Acid Formula

What are Isotones?

It is an atom containing the same neutron number but a different proton number that is called an isotone. For example, 3616 S, 3717 Cl, 3818 Ar, 3919 K, and 4020 Ca contain all 20 neutrons and are all isotones of 20. In order to tap the explosive power of the nucleus, nuclear energy and radioactivity utilize unstable isotopes of heavy elements.

Also Check – Iron (III) Hydroxide Formula

Examples of Isotopes, Isobars, and Isotones

  • Isotopes Example -: Let's consider hydrogen. It has three isotopes: protium (1H), deuterium (2H), and tritium (3H). All three have one proton, but they differ in the number of neutrons (0, 1, and 2, respectively).
  • Isobars Example - Take calcium-40 and potassium-40. Calcium-40 has 20 protons and 20 neutrons, while potassium-40 has 19 protons and 21 neutrons. Despite different atomic numbers, they have the same mass number, 40.
  • Isotones Example -  Boron-10 and carbon-14 can serve as examples. Boron-10 has 5 protons and 5 neutrons, while carbon-14 has 6 protons and 8 neutrons. These isotones share the same number of neutrons, which is 5.

Also Read: Molar Volume Formula

Identifying Isotopes, Isobars, and Isotones

  • Identifying isotopes is often straightforward since they share the same atomic number (same element) but have different atomic masses due to varying neutron counts.
  • Identifying isobars can be done by comparing the mass number. If two elements have the same mass number but different atomic numbers, they are isobars.
  • Identifying isotones requires looking at the neutron count. If two elements share the same number of neutrons but have different atomic numbers, they are isotones.

Isotopes, Isobars, and Isotones FAQs

Q1. What are Isotope, Isotones?

Ans- Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons, resulting in varying atomic masses. For example, carbon-12 and carbon-14 are isotopes of carbon. Isotones are atoms of different elements with the same number of neutrons but different atomic numbers, meaning they have distinct chemical properties. An example is carbon-14 and nitrogen-14.

Q2. What are Isotopes and Isobars with an Example?

Ans. Isotopes are atoms of the same element with different atomic masses due to varying neutron counts. For example, carbon-12 and carbon-14 are isotopes of carbon, with 6 and 8 neutrons, respectively. Isobars are atoms of different elements with the same total number of protons and neutrons. An example is calcium-40 with 20 protons and 20 neutrons and argon-40 with 18 protons and 22 neutrons.

Q3. What are 5 Examples of Isotones?

Ans. 1. Carbon-14 and nitrogen-14 Boron-10 and carbon-14 Nitrogen-15 and oxygen-15 Fluorine-19 and neon-19 Sodium-23 and magnesium-23.

Q4. What are Isotones?

Ans. Isotones are atoms of different elements that share the same number of neutrons but have distinct atomic numbers, leading to different chemical properties. For instance, carbon-14 and nitrogen-14 are isotones because they have 7 neutrons but differ in the number of protons, with carbon having 6 and nitrogen having 7.
Join 15 Million students on the app today!
Point IconLive & recorded classes available at ease
Point IconDashboard for progress tracking
Point IconMillions of practice questions at your fingertips
Download ButtonDownload Button
Banner Image
Banner Image
Free Learning Resources
Know about Physics Wallah
Physics Wallah is an Indian edtech platform that provides accessible & comprehensive learning experiences to students from Class 6th to postgraduate level. We also provide extensive NCERT solutions, sample paper, NEET, JEE Mains, BITSAT previous year papers & more such resources to students. Physics Wallah also caters to over 3.5 million registered students and over 78 lakh+ Youtube subscribers with 4.8 rating on its app.
We Stand Out because
We provide students with intensive courses with India’s qualified & experienced faculties & mentors. PW strives to make the learning experience comprehensive and accessible for students of all sections of society. We believe in empowering every single student who couldn't dream of a good career in engineering and medical field earlier.
Our Key Focus Areas
Physics Wallah's main focus is to make the learning experience as economical as possible for all students. With our affordable courses like Lakshya, Udaan and Arjuna and many others, we have been able to provide a platform for lakhs of aspirants. From providing Chemistry, Maths, Physics formula to giving e-books of eminent authors like RD Sharma, RS Aggarwal and Lakhmir Singh, PW focuses on every single student's need for preparation.
What Makes Us Different
Physics Wallah strives to develop a comprehensive pedagogical structure for students, where they get a state-of-the-art learning experience with study material and resources. Apart from catering students preparing for JEE Mains and NEET, PW also provides study material for each state board like Uttar Pradesh, Bihar, and others

Copyright © 2025 Physicswallah Limited All rights reserved.