Neutrons Isotopes Isobars Isotones - Example, Difference, FAQs

Neutrons Isotopes Isobars Isotones - Example, Difference, FAQs

Vishal kumarUpdated on 02 Jul 2025, 05:02 PM IST

Neutrons, isotopes, isobars and isotones are just common terminologies in the atomic structure because of the differences in atomic nuclei. An isotope is an atom that has the same atomic number with different neutrons, whereas an isobar has the same mass number but differs in atomic number. Isotones are atoms that have the same number of neutrons and are different in protons.

This Story also Contains

  1. What are isotones?
  2. What are Isotopes?
  3. What are Isobars?
  4. Difference Between Isotopes, Isobars and Isotones
Neutrons Isotopes Isobars Isotones - Example, Difference, FAQs
Neutrons Isotopes Isobars Isotones

What are isotones?

We can define isotones as if two species have the same number of neutrons, they are isotones. Isotone's definition is “The nuclei having the same number of nucleons are called isotones.” For them, both the atomic number (Z) and mass number are different, but the difference between (A-Z) is the same. Isotone examples are ₃Li⁷ and ₄Be⁸, ₁H³ and ₂He⁴, and ₁₁Ne²³ and ₁₂Mg²⁴.

Properties of Isotones

  • Isotones are the nuclei having the same number of neutrons in the nucleus
  • Atomic numbers and atomic masses of the isotone species are different.
  • The physical and chemical properties of isotonic species are also different. This is because these properties solely depend upon the number of electrons, not on the number of neutrons.

What are Isotopes?

The atoms of an element whose nuclei have an identical number of protons but different numbers of neutrons are called isotopes of that element. In other words, different isotopes of an element have the same atomic number (Z) but a different mass number (A). Because of the same atomic number, the isotopes of an element have the same place in the periodic table. Almost every element has isotopes. Krypton has 6, and tin has 10 isotopes. Isotopes of some elements are the following:

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Hydrogen: ₁H¹, ₁H², ₁H³

Oxygen: ₈O¹⁶, ₈ O¹⁷, ₈O¹⁸

Neon: ₁₀Ne²⁰, ₁₀Ne²¹, ₁₀Ne²²

Chlorine: ₁₇Cl³⁵, ₁₇Cl³⁷

Uranium: ₉₂U²³⁵, ₉₂U²³⁸

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The hydrogen atom has three isotopes, each having atomic number 1, but their mass numbers are 1, 2, and 3. The ₁H¹ nucleus has one proton only, the ₁H² nucleus has 1 proton and 1 neutron, and the ₁H³ nucleus has 1 proton and 2 neutrons. These elements are also known as isotonic elements.

Properties of Isotopes

1. All isotopes of an element have the same number of electrons, and an atom has an equal number of electrons and protons. Therefore, the chemical properties of different isotopes of an element are the same.

2. The mass number (that is, the number of nucleons) of different isotopes of an element is different. Ha Hence, their physical properties are not the same.

3. Chemical properties are the same; two isotopes of the same element cannot be separated by any chemical process. To separate them, physical processes based on atomic mass, like gaseous diffusion, are used.

4. Among isotopes of the same element, some may be stable and some radioactive. This is so because of the difference in their nuclear structure. For example, ₆C¹² is stable while ₆c¹⁴ is radioactive.

What are Isobars?

The nuclei that have an identical number of nucleons but different numbers of protons and different numbers of neutrons are called isobars. Their atomic number (Z) is different, but the atomic number (A) is the same. Therefore, they have different places in periodic numbers and also differ in chemical properties. Since in isobars, the numbers of fundamental particles are different, they differ in physical properties also. The nuclei of isobars belong to different elements. Some examples of isobars are ₁H³ and ₂He³, ₆C¹⁴ and ₇N¹⁴, ₈O¹⁷ and ₉F¹⁷.

Properties of Isobars

1. The total number of nucleons (protons + neutrons) is the same in isobars. Hence it can be stated that they have the same atomic masses.

2. Isobars exhibit different numbers of protons and different atomic numbers and hence represent different elements.

3. Isobars have differents physical and chemical properties, because the physical and chemical usually depends on the atomic number. If the atomic numbers are different then properties also differes.

Difference Between Isotopes, Isobars and Isotones

Isotopes

Isobars

Isotones

The atoms of an element whose nuclei have the same number of protons but different numbers of neutrons are called isotopes.

The nuclei that have an identical number of nucleons but different numbers of protons and different numbers of neutrons are called isobars.

The nuclei having identical numbers of neutrons are called isotones.

Their atomic number (Z) is the same, but their mass number (A) is the same.

Their atomic number (Z) is different, but their mass number (A) is the same.

Their atomic number (Z) and mass number (A) are different, but the value of (A - Z) is the same.

Almost all the isotopes have identical chemical and physical properties.

Isobars have different physical properties and chemical properties.

Isotones have different physical and chemical properties.

E.g., ₁H¹, ₁H², ₁H³

E.g., ₁H³ and ₂He³

E.g., ₃Li⁷ and ₄Be⁸,


Frequently Asked Questions (FAQs)

Q: What is the concept of isotopic anomalies in cosmochemistry and how do they inform our understanding of the early solar system?
A:
Isotopic anomalies are deviations from the expected isotopic ratios found in solar system materials. These anomalies in meteorites and other extraterrestrial samples provide evidence for the heterogeneous distribution of matter in the early solar
Q: How do isotopes affect the Zeeman effect in atomic spectroscopy?
A:
Different isotopes can show variations in the Zeeman effect due to differences in their nuclear magnetic moments. This leads to isotope-specific splitting patterns of spectral lines in magnetic fields, which can be used for isotope identification and studying hyperfine structure in atoms.
Q: What is the significance of magic numbers in the stability of isotopes and isotones?
A:
Magic numbers (2, 8, 20, 28, 50, 82, 126) represent filled nuclear shells, leading to enhanced stability. Nuclei with magic numbers of either protons or neutrons (or both) are more abundant and resistant to radioactive decay. This concept is crucial for understanding nuclear structure and the limits of nuclear stability.
Q: How do isotopes contribute to our understanding of stellar nucleosynthesis pathways?
A:
The abundance patterns of different isotopes in stars and meteorites provide clues about the nuclear processes occurring in stellar interiors. For example, the presence of certain neutron-rich isotopes indicates the occurrence of the r-process in supernovae, while other isotopic signatures point to s-process in red giants.
Q: What is the concept of isotope dilution and how is it used in analytical chemistry?
A:
Isotope dilution is a technique where a known amount of an isotopically enriched substance is added to a sample. By measuring the resulting isotope ratio, the concentration of the element in the original sample can be determined with high accuracy. This method is widely used in trace element analysis.
Q: How do isotopes affect nuclear spin statistics and rotational spectroscopy?
A:
The nuclear spin of isotopes affects the allowed rotational energy levels in molecules through nuclear spin statistics. This influences the intensity patterns in rotational spectra. For example, the different nuclear spins of hydrogen and deuterium lead to distinct rotational spectra for H2 and D2.
Q: What is the concept of isomer shifts in Mössbauer spectroscopy?
A:
Isomer shifts in Mössbauer spectroscopy arise from differences in the electron density at the nucleus between the source and absorber atoms. This can be affected by the chemical environment of the atom. Studying these shifts provides information about the oxidation state and bonding of atoms in materials.
Q: How do isotopes contribute to the field of archaeometry?
A:
In archaeometry, isotopic analysis is used to date artifacts and study ancient materials. Techniques like radiocarbon dating (using carbon-14) and potassium-argon dating utilize the decay of specific isotopes to determine the age of organic and inorganic materials, respectively.
Q: What is the concept of isotope shifts in atomic spectroscopy?
A:
Isotope shifts are small differences in the spectral lines of different isotopes of the same element. They arise from differences in nuclear mass and size, affecting electron energy levels. These shifts provide information about nuclear structure and are used in high-precision spectroscopy and isotope separation.
Q: What is the significance of the valley of stability in the chart of nuclides?
A:
The valley of stability is the region in the chart of nuclides where the most stable isotopes of each element are found. It represents the optimal neutron-to-proton ratios for nuclear stability. Understanding this concept is crucial for predicting the behavior of exotic nuclei and the limits of nuclear existence.