Isotopes and Isobars - Meaning, Definition, Examples, Types, FAQs

Edited By Team Careers360 | Updated on Jul 02, 2025 04:35 PM IST

What are isotopes and isobars?

Those things have the same number of atoms, but a much different number is called isotopes. Isotopes occur due to the presence of a different number of neutrons in structures with the same atomic number as the weight number of the total number of neutrons and protons. Most but not all substances contain isotopes. Hydrogen isotopes are protium (one proton and no neutron), deuterium (one proton and one neutron) and tritium (one proton and two neutrons). The chemical properties of the Isotopes and Isobars are similar in that they have the same number of protons and that is why the same number of electrons determines the chemical properties of an object.

NEET 2025: Mock Test Series | Syllabus | High Scoring Topics | PYQs

JEE Main: Study Materials | High Scoring Topics | Preparation Guide

JEE Main: Syllabus | Sample Papers | Mock Tests | PYQs

This Story also Contains

What are isotopes and isobars?
Define isotopes
Define isobar
Physical and chemical properties of Isotopes
Types of Isotopes
Examples of Isotopes and Isobars

Isobars, on the other hand, have atoms with the same number of weights but different atoms.

The atomic number of carbon is 6 and nitrogen is 7 respectively.

Carbon-14 isotope carbon is 14 times the same as nitrogen which is why carbon-14 and nitrogen are isobars.

The atomic number plays a very important role in the placement of elements in the present-day table. Represents the number of protons and therefore the number of electrons in an atom. The number of electrons in an atom controls its chemical activity. Genetic research has revealed their effectiveness in a variety of ways.

Also read -

Define isotopes

isotope, one of two or more atoms of a chemical substance with the same number of atoms and a timeline and similar chemical behavior but with a variety of atoms and physical structures. Every chemical substance contains one or more isotopes.

Example of Isotopes

Carbon-12, carbon-13, and carbon-14 are three isotopes of elemental carbon with the numbers 12, 13 and 14, respectively

Define isobar

Isobar is a line of thought or a line on a map or chart that connects or marks areas of equal barometric pressure.

Isobar is one or two atoms or objects with the same atomic weight or multiple numbers but different atomic numbers.

Isobars are atoms of different objects that have the same number of numbers but different atomic numbers. For example, two elements of calcium and argon. The number of electrons in these atoms varies, but the maximum number of the two is 40.17

Isobars are types of atoms that have the same number of masses (A), but a different number of atoms (Z).

Examples of isobars

14,6C; 14,8O; 14,7N

What is Isobar in Chemistry?

Isobar is a different organ in the chemical field but has the same physical properties. Therefore, we can say that isobar chemistry are those objects that have a different atomic number but the same number. Their chemical properties are different because there is a difference in the number of electrons. It has the same atomic weight but a different atom does not. This is because the extra number of neutrons compensates for the difference in the number of nucleons. Isobar have same number of protons and neutrons in total. Some Examples of Isotopes and Isobars are steel and nickel. Both have the same plural number 58 and the metal atomic number is 26, and the nickel atomic number is 28.

What are Isotopes?

Let us take the example of two objects of the same color, the same appearance of the body, which you cannot distinguish between the two. But when you weigh the weight of these two things you find that they are different.

You can actually relate the concepts of isotopes with the given example.

Atomic mass is the sum of some protons and the number of neutrons and the number of atoms is equal to the number of protons. In the element, the number of protons remains the same, but the number of neutrons continues to change.

From the above description of the atomic mass and the atomic number, we can conclude that isotopes are those that have the same atomic number and a different number of sizes.

Hydrogen isotopes: There are three hydrogen Isotopes and Isobars and these are protium, deuterium, and tritium.

Definition of Isobar.

Isobars are described as

"Atoms have the same number of nucleons".

Isobars of different types of chemical elements have a different atomic number and have the same atomic mass number.

Alfred Walter Stewart in 1918 proposed the word isobars. It is derived from the Greek word for isos meaning equality and baros means weight.

Also Read:

What is Isotope?

The term “isotope” basically refers to the separation of the atomic weight or the mass of an object.

Because of the unequal number of neutrons, genetic isotopes usually have a different weight. Normally, objects with an odd atomic number would have one or two stable atoms and objects with atomic values would generally have three or more stable isotopes. However, there are alternatives such as carbon, helium, and beryllium.

Isotope is usually indicated or identified by the name of an object initially followed by a link and a weight number.

Physical and chemical properties of Isotopes

When we talk about the chemical properties of the isotopes of a given object they are almost identical or similar. Different isotopes exhibit almost identical chemical behavior. However, when it comes to the physical properties of isotopes such as mass, the point of melting or boiling, the density, and the point of freezing are all different.

Types of Isotopes

Isotopes are said to be stable or radioactive. Therefore, isotopes that use radio waves are called radioisotopes or radionuclides.

Non-radioactive isotopes are known as stable isotopes or stable nuclides.

According to findings, there are 339 nuclides or isotopes that occur naturally on the planet earth.

Of these, 286 are said to be the largest nuclides believed to have existed since the inception of the Solar System.

Facts of Element Isotopes

Here are some interesting facts about isotopes.

Most organic matter is a combination of several isotopes.

They are also known as Nuclides.

About 1000 volatile isotope currently exist. Some of them occur in nature while others are made in laboratories

About 20 objects have only one stable isotope. A few of them include gold, aluminum, phosphorus, fluorine and sodium.

A variety of isotopes are used in such fields as carbon dioxide, nuclear reactors and therapeutic purposes.

Related Topics,

NEET Highest Scoring Chapters & Topics

This ebook serves as a valuable study guide for NEET exams, specifically designed to assist students in light of recent changes and the removal of certain topics from the NEET exam.

Download EBook

Examples of Isotopes and Isobars

Examples of Isotope

Common examples are hydrogen and carbon isotopes. Apart from these some of the most common isotope examples include - Tin has 22 isotopes, Zinc has 21 known isotopes, Neon is a mixture of 3 isotopes, natural xenon has a combination of 9 isotopes stable, Nickel has 14 known isotopes.

Isobars examples

Argon, potassium, and calcium with atoms of the same number 40.

18Ar40, 19K40, 20Ca40 where 18, 19 and 20 shown as payloads are the atomic numbers of three things in a row are isobars. As atomic numbers are different their chemical properties are also different. The word isotope is derived from two Greek words that isos and topos continue to translate “in the same place”. So the idea of using this term is that the isotopes of a single object are found in the same place in the timeline. The term was first used by Margaret Todd, a Scottish physician, and author during a consultation with radiochemist doctor Frederick Soddy. The name was coined in 1913.

Also check-

NCERT Chemistry Notes:

Frequently Asked Questions (FAQs)

1. 1.Name three oxygen isotopes.

16O, 17O, and 18O.

2. 2.How are isotopes formed?

Atoms have same number of protons but different number of neutrons along with protons are called isotopes.

3. 3.Give some examples of stable isotopes.

Vanadium, carbon, calcium, potassium are stable isotopes.

4. 4.What radiation is the unstable isotope emitting?

Unstable isotopes emit alpha, beta and gamma rays

5. 5.What are isobars?

The atoms that have the same number of nucleons. Isobars of different chemical elements have different atomic numbers but have the same mass number.

6. 6.Give some examples of isobars.

40S, 40Ar, 40Ca. 40Cl, and 40K.

7. How do isobars differ in their nuclear structure?

Isobars have the same number of nucleons (protons + neutrons) but different numbers of protons and neutrons.

8. What is the concept of nuclear isomers?

Nuclear isomers are excited states of atomic nuclei with relatively long half-lives, often involving specific arrangements of protons and neutrons.

9. What is the island of stability in nuclear physics?

The island of stability is a theoretical cluster of superheavy elements with relatively long half-lives due to their specific neutron and proton numbers.

10. What are magic numbers in nuclear physics?

Magic numbers (2, 8, 20, 28, 50, 82, 126) represent specific numbers of protons or neutrons that result in particularly stable nuclei.

11. What are isotopes?

Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons. They have the same atomic number but different mass numbers.

12. What is the mass number of an atom?

The mass number is the total number of protons and neutrons in an atom's nucleus.

13. What is isotopic labeling?

Isotopic labeling involves replacing specific atoms in a molecule with their isotopes to track chemical reactions or biological processes.

14. What is the difference between enriched and depleted uranium?

Enriched uranium has a higher proportion of the fissile uranium-235 isotope, while depleted uranium has a lower proportion compared to natural uranium.

15. How are isotopes represented in notation?

Isotopes are represented as [Mass Number][Element Symbol]. For example, carbon-12 is written as 12C.

16. What is the difference between 12C and 14C?

12C and 14C are isotopes of carbon. 12C has 6 protons and 6 neutrons, while 14C has 6 protons and 8 neutrons.

17. What is the importance of deuterium in nuclear physics?

Deuterium, an isotope of hydrogen with one proton and one neutron, is important in nuclear fusion reactions and as a neutron moderator in nuclear reactors.

18. What is the neutron-to-proton ratio?

The neutron-to-proton ratio is the number of neutrons divided by the number of protons in an atom's nucleus. It affects nuclear stability.

19. What is isotopic abundance?

Isotopic abundance refers to the relative proportion of different isotopes of an element found in nature.

20. Why do isotopes have the same chemical properties?

Isotopes have the same chemical properties because they have the same number of electrons in their outer shell, which determines chemical behavior.

21. How do isotopes affect an element's physical properties?

Isotopes can slightly affect physical properties like melting point, boiling point, and density due to mass differences.

22. How do isotopes affect an element's atomic mass?

The atomic mass of an element is the weighted average of its naturally occurring isotopes' masses.

23. Can isotopes be separated?

Yes, isotopes can be separated using techniques like mass spectrometry or centrifugation, which exploit their slight mass differences.

24. How do isotopes impact the periodic table?

Isotopes don't change an element's position in the periodic table because the atomic number (number of protons) remains constant.

25. What are radioactive isotopes?

Radioactive isotopes are unstable isotopes that decay over time, emitting radiation in the process.

26. How do isotopes affect nuclear stability?

The ratio of neutrons to protons in an isotope's nucleus affects its stability. Some combinations are more stable than others.

27. How are isotopes used in carbon dating?

Carbon dating uses the decay of radioactive carbon-14 to estimate the age of organic materials.

28. What are isotones?

Isotones are atoms of different elements that have the same number of neutrons but different numbers of protons.

29. How are isotopes used in medical imaging?

Radioactive isotopes are used as tracers in medical imaging techniques like PET scans to visualize metabolic processes in the body.

30. How do isotopes differ from isobars?

Isotopes have the same atomic number (number of protons) but different mass numbers, while isobars have the same mass number but different atomic numbers.

31. What is the difference between isotopic and isobaric species?

Isotopic species have the same number of protons but different numbers of neutrons, while isobaric species have the same mass number but different numbers of protons and neutrons.

32. What is isotope fractionation?

Isotope fractionation is the process by which the relative abundances of isotopes change during physical or chemical processes due to their slight mass differences.

33. What is the difference between natural and artificial isotopes?

Natural isotopes occur in nature, while artificial isotopes are created in laboratories or nuclear reactors.

34. How do isotopes contribute to nuclear energy production?

Certain isotopes, like uranium-235, can undergo nuclear fission, releasing energy that can be harnessed in nuclear power plants.

35. How do isotopes affect atomic mass spectroscopy?

Isotopes produce distinct peaks in mass spectra, allowing for the identification and quantification of different isotopes of an element.

36. How do isotopes impact radiometric dating?

Radiometric dating uses the decay of radioactive isotopes to determine the age of rocks, fossils, and other materials.

37. How do isotopes affect nuclear magnetic resonance (NMR) spectroscopy?

Different isotopes of the same element can have different nuclear spins, affecting their behavior in NMR spectroscopy.

38. What is the difference between fission and fusion in terms of isotopes?

Fission involves splitting heavy isotopes into lighter ones, while fusion combines light isotopes to form heavier ones. Both processes release energy.

39. How do isotopes contribute to our understanding of climate history?

The ratios of certain isotopes in ice cores, sediments, and fossils provide information about past climates and environmental conditions.

40. What is the nuclear shell model?

The nuclear shell model is a theoretical model that explains the structure of atomic nuclei, including the stability of certain isotopes with "magic numbers" of protons or neutrons.

41. How do isotopes affect chemical reaction rates?

Isotopes can affect reaction rates through the kinetic isotope effect, where heavier isotopes generally react more slowly than lighter ones.

42. What is isotope dilution?

Isotope dilution is an analytical technique that uses known amounts of isotopically enriched substances to determine the concentration of elements in a sample.

43. How are isotopes used in food tracing?

The unique isotopic compositions of different geographical regions can be used to trace the origin of food products.

44. How do isotopes contribute to paleoclimatology?

The ratios of oxygen and hydrogen isotopes in ancient materials like ice cores and sediments provide information about past climate conditions.

45. What is the neutron activation analysis?

Neutron activation analysis is a technique that uses neutron bombardment to create radioactive isotopes, which can then be used to identify and quantify elements in a sample.

46. How do isotopes affect atomic clocks?

Certain isotopes, like cesium-133, are used in atomic clocks due to their precise and stable energy level transitions.

47. What is the isotope effect in superconductivity?

The isotope effect in superconductivity refers to the change in the critical temperature of a superconductor when its isotopic composition is altered.

48. How are isotopes used in environmental studies?

Isotopes are used as tracers to study water cycles, pollution dispersion, and ecosystem dynamics in environmental research.

49. How do isotopes affect nuclear magnetic moments?

Different isotopes of an element can have different nuclear magnetic moments, affecting their behavior in magnetic fields and spectroscopic techniques.

50. How do isotopes contribute to the study of metabolic pathways?

Isotopically labeled compounds can be used to trace metabolic pathways in organisms, helping to understand biochemical processes.

51. What is the significance of the deuterium-tritium fusion reaction?

The deuterium-tritium fusion reaction is considered one of the most promising for future nuclear fusion energy production due to its relatively high reaction rate and energy yield.

52. How do isotopes affect the boiling and melting points of substances?

Heavier isotopes generally have slightly higher boiling and melting points due to stronger intermolecular forces resulting from their greater mass.

53. What is the role of isotopes in nuclear forensics?

Isotopic ratios and compositions are used in nuclear forensics to determine the origin and history of nuclear materials.

54. How do isotopes contribute to the study of ocean circulation?

Naturally occurring and artificial isotopes serve as tracers to study ocean currents, mixing processes, and circulation patterns.

55. What is the concept of isotopic fractionation in geochemistry?

Isotopic fractionation in geochemistry refers to the separation of isotopes during geological processes, which can provide information about past environmental conditions and geological history.

56. How do isotopes affect the half-life of radioactive elements?

Different isotopes of the same element can have vastly different half-lives, ranging from fractions of a second to billions of years, depending on their nuclear stability.