Intermediate Topic 23 of 1102 Atomic Structure & Periodicity
Isotones
Nuclides having the same number of neutrons but different numbers of protons.
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In-depth explanation of Isotones
Isotones are nuclides that have the same neutron number N but different proton numbers Z. Because they contain the same number of neutrons, they are different elements with different chemistry but related nuclear structure. Isotones can differ in stability, and nuclei with magic neutron numbers are especially stable within an isotone series. Comparing isotones helps physicists test models of nuclear structure and shell effects. The term is less familiar than isotope or isobar, but it describes a distinct grouping of nuclides.
Going deeper: Isotones
Key ideas: Isotones have the same number of neutrons but different Z and A, such as 14C and 15N (8 neutrons each) or 36S, 37Cl, 38Ar (all with 20 neutrons). To test, compute N = A - Z for each nuclide and compare.
Common mistakes and connections: Students mix isotones up with isotopes and isobars, and often subtract the wrong number. Isotones are mostly a nuclear structure concept and have different chemistry. They connect to magic numbers, since isotones with N equal to 2, 8, 20, 28, 50, 82 or 126 are especially stable.
Visualization of Isotones
Each of these nuclides has exactly 20 neutrons but a different proton number, making them isotones of different elements. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Carbon-14 and nitrogen-15 are isotones, since each has 8 neutrons.
Frequently asked questions about Isotones
What is Isotones?
Nuclides having the same number of neutrons but different numbers of protons.
Is Isotones a beginner, intermediate or advanced topic?
Isotones is a intermediate topic in Atomic Structure & Periodicity. It builds on the vocabulary of beginner topics in this area.
What should I learn before Isotones?
Study these earlier topics in Atomic Structure & Periodicity first: Mass Number, Isotopes, Isobars.
What comes after Isotones?
The next topics in Atomic Structure & Periodicity are Relative Atomic Mass and Atomic Mass Unit.
Can I practise Isotones with quizzes?
Yes. The interactive lesson includes a self-check question on Isotones, and the Atomic Structure & Periodicity quiz draws on every topic in this area.
Where Isotones fits in Atomic Structure & Periodicity
Isotones is topic 23 of 115 in Atomic Structure & Periodicity.