What does isotopy mean?
Isotopy is a technical noun in nuclear physics and chemistry for the relationship between isotopes: atoms of the same element share an identical number of protons but differ in their numbers of neutrons, giving them different mass numbers and often different nuclear properties. In this sense, isotopy describes a pattern or relationship, whereas an isotope is one member of that pattern; carbon-12, carbon-13, and carbon-14 are familiar examples of isotopes. The word is chiefly used in scientific and educational contexts, especially in discussions of elements, nuclides, and isotopic abundance. Because it names an abstract relationship rather than a specific particle, it is less common in everyday speech than isotope. Its Greek-derived formation, iso- meaning “equal” and -topy from topos, “place,” captures the historical idea of different forms occupying the same place in the periodic system. Knowing isotopy helps distinguish the defining equivalence of isotopes from their measurable differences in mass and composition.
nounIsotopy is the phenomenon in which two or more atoms of the same element have the same number of protons but different numbers of neutrons, and therefore different mass numbers. It names the relationship among isotopes rather than an individual isotope.
- The phenomenon of two or more atoms or nuclides having the same atomic number but different mass numbers because they contain different numbers of neutrons.
"Carbon-12, carbon-13, and carbon-14 illustrate isotopy because all three forms of carbon contain six protons but different numbers of neutrons."
"Their measurements of carbon showed clear isotopy: the sample contained both carbon-12 and carbon-13."
"The study examined isotopy across several elements to determine how their atoms differ in neutron number."
The regular plural is isotopies, although singular usage is much more common in technical writing.
"The paper discusses the isotopies of several elements across the periodic table."
Same element, different neutron count: that is isotopy, the family pattern behind every isotope.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does isotopy come from?
Isotopy entered English as a scientific term built from iso-, meaning “equal,” and the Greek-derived element -topy, ultimately associated with topos, meaning “place.” Its wording reflects the idea that isotopes occupy the same place in the periodic table because their atomic numbers are equal. Related English forms include isotope, isotopic, and isotopically, all expressing the same “equal place” concept.
Related word forms
How isotopy is actually used
A formal, highly specialized term used mainly in physics and chemistry; it is uncommon in general prose.
Easily confused with isotopy
Isotopy is the relationship among different forms of an element, whereas an isotope is one particular form of that element.