What the hell is the actual difference between an isotope and a nuclide??

Submitted by amypinecone t3_11wj8gk in askscience

I've been spending the past few hours looking everywhere for answers and I just can't find anything that makes sense to me. Everywhere I looked, the definitions given one after the other for isotopes vs nuclides were almost exactly the same, but then they'd say something vague afterwards like "but there are a few aspects that make them different to eachother" and then it wouldn't elaborate further. Like, all the articles and websites would describe isotopes as "the sum of the neutrons and protons in an atom" and then they would describe nuclides as "the combination of neutrons and protons in an atom". I even interrogated an AI model on this in depth and got basically the same vague confusing answers. What is the difference in those definitions?? Please help.

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RobusEtCeleritas t1_jczr6i3 wrote

They're often used interchangeably, but that's not technically correct.

A nuclide is a collection of nucleons defined by its number of protons (Z) and number of neutrons (N).

Isotopes are nuclides that have the same Z. So they are the same element, but they can have different numbers of neutrons.

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amypinecone OP t1_jczsxk7 wrote

does that essentially mean that nuclide is more used generally as just describing something by its number of protons and neutrons (as opposed to just describing an element it with it's atomic number for example), and then the term isotopes would more often be used when talking about variations of something (such as carbon having carbon-12, 13, and 14)? sorry if I have it confused still

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QuentaAman t1_jd52mw9 wrote

Just think of nuclide as describing a random atom the has Z protons and N neutrons whereas isotopes is refering to a specific element (Z) with varying number of neutrons N.

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IllustriousArtist109 t1_jd44fsd wrote

Carbon-14 and carbon-12 are different isotopes of carbon ... right?

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EDITED to correct

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RobusEtCeleritas t1_jd4j0yn wrote

>Carbon-14 and carbon-12 are different isotopes of carbon ... right?

Yes.

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dirschau t1_jd17svs wrote

So a nuclide is just a technical term for "(specific) atomic nucleus but without any electrons"?

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drhunny t1_jd0wicd wrote

Isotopes are nuclides with the same number of protons. C-12,. C-13, C-14 are on the "6 proton isotope". Isotones are nuclides that have the same number of neutrons. H-3 and He-4 are on the n=2 isotone. Similar to how places at the same atmospheric pressure are on an isobaric line.

Weirdly, "isobar" is also a term in nuclear physics where it means same number of total neutron plus protons. I think it comes from from "baryon" whereas in meteorology it comes from "barometer"

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Ridley_Himself t1_jd16gt8 wrote

I had thought it came from them having about the same atomic weight iso=same, bar=weight/heavy.

But then baryon has the same root.

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Hoihe t1_jd2cymj wrote

/u/drhunny within Mass Spectrometry, we also use "isobar" to refer to fragments that may share the same nominal mass.

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El_Sephiroth t1_jd1xjvp wrote

Bar = unit of pressure. Isobar = same pressure everywhere. Baryon does not have the same roots. It is then Isobaryon but when talking nuclear physics you can shorten it because you usually don't talk about pressure so Isobar.

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Ridley_Himself t1_jd5po6a wrote

Bar is a unit of pressure, but it is still derived from the Greek root barus, meaning heavy. So we get a few words from the root such as barometer, isobar, baryon (“heavy particle“), barium (due to the high density of barium minerals).

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