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Isotopes and Isobars

Last updated date: 18th May 2024
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What are Isobars and isotopes?

Isobar is an element that differs in chemical properties, but it has similar physical properties. Hence, we can say that isobars are elements that have a different atomic number but the same mass number. Also, they have a different chemical property because there is a difference in the electron count. An isobar contains the same atomic mass but a different atomic number because an added number of neutrons recompense the number of nucleons.

An example of two isotopes and isobars is nickel and iron. These both have the same mass number, which is 58, whereas the atomic number of nickel is 28, and the atomic number of iron is 26.

Let us consider an example of 2 things, which appear to be the same in colour and in their physical appearance, such that we cannot distinguish between them. However, when we measure the weight of these two, then we find a difference. We can relate the isotopes concept with this example.

As we all know, every atom is made of electrons, protons, and neutrons. The nucleus is made of only protons and neutrons, and the electrons revolve around the nucleus. Atomic mass can be defined as the sum of a few protons and the number of neutrons. Moreover, the atomic number is equal to the number of protons. The number of protons is always the same in an element, but the number of neutrons keeps on changing.

Isotopes are atoms, wherein the number of neutrons differs from each other, and the number of protons remains the same. From the definition of atomic mass and the atomic number, which is given above, we can conclude that isotopes are the elements that have a similar atomic number with different mass numbers.

Examples of Isobars

Potassium, Argon, and calcium contain atoms of the same mass number 40.

19K40, 18Ar40, 20Ca40, where 19, 18, 20 represented as subscripts are the atomic numbers of the 3 elements, respectively, are the isobars. Because their atomic numbers vary, their chemical properties also vary. The structure of potassium, argon, and calcium is represented below.

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Examples of Isotopes

Let us understand something about the isotopes of hydrogen.

  • There are 3 isotopes of hydrogen: protium, deuterium, and tritium

  • All these have the same number of protons, but they differ in the number of neutrons.

  • In protium, the number of neutrons is 0; in deuterium, it is 1; in tritium, the number of neutrons is 2.

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Let us look at the difference between isotopes and isobars, as tabulated below.

Difference Between Isotopes and Isobars



These are the chemical elements that have the same mass.

These are the different atomic structures of the same element.

The physical properties are often similar.

In general, there are different physical properties.

These have equal atomic masses.

These have different atomic masses.

Their chemical elements are different.

Their chemical elements are the same but in different forms.

They have different atomic numbers.

They contain the same atomic numbers.

Uses of Isotopes

Uses of Isotopes in Medicine

  • Gamma-rays that are emitted from cobalt-60 can be used in radiotherapy for cancer treatment.

  • Superficial cancers like skin cancer are treated by less penetrating radiation from the strontium-90 or phosphorus-32.

  • A heart pacemaker that contains plutonium-238 can be used to regulate the patients’ heartbeats with heart problems.

  • Iodine-131 can also be used in thyroid disease treatment.

  • Carbon-14 is used to estimate the bone’s age, fossils, or wood by measuring the fraction of carbon-14 that it contains.

Isotope Uses in Agriculture

  • The phosphate and metabolism uptake of phosphorus by plants is studied using a phosphate fertilizer that contains phosphorus-32.

  • Furthermore, the radioactive tracer studies by using carbon-14 have helped understand protein synthesis and photosynthesis.

Isotope Uses in the Industrial Sector

  • Sodium-24 is used to trace the gas or oil pipe leaks and ventilating systems.

  • Radiation from krypton-85 is used to control the plastic sheet thickness in the industry.

  • Cobalt-60’s gamma rays are passed through food to destroy the bacteria, which causes food to spoil without changing the flavor, quality, or texture of the food.

Uses of Isobars

Let us look at a few uses of isobars:

  • Nuclear reactors can use uranium isobars.

  • Iodine’s isobars are used in goiter treatment.

  • For cancer treatment, isobars of cobalt can be used.

FAQs on Isotopes and Isobars

1. Explain the importance of isobar chemistry?

Atmospheric pressure differs according to location, even if it is at the same altitude. Isobars give reference lines running accompanying a path, where the pressure is the same along the line. With a series of lines, every marking place where the pressures have a similar specified value, which is a map, the user can get a reasonable estimate at any map location. He can do so either by reading the line’s pressure if it happens to pass through the interesting location exactly or by the interpolation depending on the nearest isobars, which is the one at a higher pressure compared to the interesting location and the isobar nearest, with lower pressure.

2. Why do elements have isobars and isotopes?

Due to the presence of a different number of neutrons in atoms of the same element, it has different isotopes. Different elements can have different isobars due to the same mass number (s) of neutrons, and protons.