Isotopes of nobelium

Key takeaways

Isotopes of nobelium belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Isotopes of nobelium to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Isotopes of nobelium from memory before moving on to harder problems.

Reference excerpt

Nobelium (102No) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes. The first isotope to be synthesized (and correctly identified) was 254No in 1966. There are fourteen known radioisotopes, which are 248No to 260No and 262No, and many isomers. The longest-lived isotope is 259No with a half-life of 58 minutes. The longest-lived isomer is 251m1No with a half-life of 1.02 seconds.

List of isotopes

Nucleosynthesis

Cold fusion 208Pb(48Ca,xn)256−xNo (x=1,2,3,4) This cold fusion reaction was first studied in 1979 at Flerov Laboratory of Nuclear Reactions (FLNR). Further work in 1988 at GSI measured EC and SF branchings in 254No. In 1989, the FLNR used the reaction to measure SF decay characteristics for the two isomers of 254No. The measurement of the 2n excitation function was reported in 2001 by Yuri Oganessian at the FLNR. Patin et al. at the LBNL reported in 2002 the synthesis of 255–251No in the 1-4n exit channels and measured further decay data for these isotopes. The reaction has recently been used at Jyväskylän Yliopisto Fysiikan Laitos (JYFL) using the RITU set-up to study K-isomerism in 254No. The scientists were able to measure two K-isomers with half-lives of 275 ms and 198 s, respectively. They were assigned to 8− and 16+ K-isomeric levels. The reaction was used in 2004–5 at the FLNR to study the spectroscopy of 255–253No. The team were able to confirm an isomeric level in 253No with a half-life of 43.5 s.

208Pb(44Ca,xn)252−xNo (x=2) This reaction was studied in 2003 at the FLNR in a study of the spectroscopy of 250No.

207Pb(48Ca,xn)255−xNo (x=2) The measurement of the 2n excitation function for this reaction was reported in 2001 by Yuri Oganessian and co-workers at the FLNR. The reaction was used in 2004–5 to study the spectroscopy of 253No.

206Pb(48Ca,xn)254−xNo (x=1,2,3,4) The measurement of the 1-4n excitation functions for this reaction were reported in 2001 by Yuri Oganessian and co-workers at the FLNR. The 2n channel was further studied by the GSI to provide a spectroscopic determination of K-isomerism in 252No. A K-isomer with spin and parity 8− was detected with a half-life of 110 ms.

204Pb(48Ca,xn)252−xNo (x=2,3) The measurement of the 2n excitation function for this reaction was reported in 2001 by Yuri Oganessian at the FLNR. They reported a new isotope 250No with a half-life of 36 μs. The reaction was used in 2003 to study the spectroscopy of 250No.They were able to observe two spontaneous fission activities with half-lives of 5.6 μs and 54 μs and assigned to 250No and 249No, respectively. The latter activity was later assigned to a K-isomer in 250No. The reaction was reported in 2006 by Peterson et al. at the Argonne National Laboratory (ANL) in a study of SF in 250No. They detected two activities with half-lives of 3.7 μs and 43 μs and both assigned to 250No, the latter associated with a K-isomer. In 2020, a team at FLNR repeated this reaction and found a new 9.1-MeV alpha particle activity correlated to 245Fm and 241Cf, which they assigned to the new isotope 249No.

Hot fusion 232Th(26Mg,xn)258−xNo (x=4,5,6) The cross sections for the 4-6n exit channels have been measured for this reaction at the FLNR.

238U(22Ne,xn)260−xNo (x=4,5,6) This reaction was first studied in 1964 at FLNR. The team were able to detect decays from 252Fm and 250Fm. The 252Fm activity was associated with an ~8 s half-life and assigned to 256102 from the 4n channel, with a yield of 45 nb. They were also able to detect a 10 s spontaneous fission activity also tentatively assigned to 256102. Further work in 1966 on the reaction examined the detection of 250Fm decay using chemical separation and a parent activity with a half-life of ~50 s was reported and correctly assigned to 254102. They also detected a 10 s spontaneous fission activity tentatively assigned to 256102. The reaction was used in 1969 to study some initial chemistry of nobelium at the FLNR. They determined eka-ytterbium properties, consistent with nobelium as the heavier homologue. In 1970, they were able to study the SF properties of 256No. In 2002, Patin et al. reported the synthesis of 256No from the 4n channel but were unable to detect 257No. The cross section values for the 4-6n channels have also been studied at the FLNR.

238U(20Ne,xn)258−xNo This reaction was studied in 1964 at FLNR. No spontaneous fission activities were observed.

236U(22Ne,xn)258−xNo (x=4,5,6) The cross sections for the 4-6n exit channels have been measured for this reaction at the FLNR.

235U(22Ne,xn)257−xNo (x=5) This reaction was studied in 1970 at the FLNR. It was used to study the SF decay properties of 252No.

233U(22Ne,xn)255−xNo The synthesis of neutron deficient nobelium isotopes was studied in 1975 at the FLNR. In their experiments they observed a 250 s SF activity, which they tentatively assigned to 250No in the 5n exit channel. Later results have not been able to confirm this activity and it is currently unidentified.

242Pu(18O,xn)260−xNo (x=4?) This reaction was studied in 1966 at the FLNR. The team identified an 8.2 s SF activity tentatively assigned to 256102.

241Pu(16O,xn)257−xNo This reaction was first studied in 1958 at the FLNR. The team measured ~8.8 MeV alpha particles with a half-life of 30 s and assigned to 253,252,251102. A repeat in 1960 produced 8.9 MeV alpha particles with a half-life of 2–40 s and assigned to 253102 from the 4n channel. Confidence in these results was later diminished.

239Pu(18O,xn)257−xNo (x=5) This reaction was studied in 1970 at the FLNR in an effort to study the SF decay properties of 252No.

239Pu(16O,xn)255−xNo This reaction was first studied in 1958 at the FLNR. The team were able to measure ~8.8 MeV alpha particles with a half-life of 30 s and assigned to253,252,251102. A repeat in 1960 was unsuccessful and it was concluded the first results were probably associated with background effects.

243Am(15N,xn)258−xNo (x=4) This reaction was studied in 1966 at the FLNR. The team were able to detect 250Fm using chemical techniques and determined an associated half-life significantly higher than the reported 3 s by Berkeley for the supposed parent 254No. Further work later the same year measured 8.1 MeV alpha particles with a half-life of 30–40 s.

243Am(14N,xn)257−xNo This reaction was studied in 1966 at the FLNR. They were unable to detect the 8.1 MeV alpha particles detected when using a N-15 beam.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Isotopes of nobelium

Start with the simplest possible case. Write down what Isotopes of nobelium claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Isotopes of nobelium before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Isotopes of nobelium ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Isotopes of nobelium

In research: Isotopes of nobelium appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Isotopes of nobelium in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Isotopes of nobelium is common in secondary-school and first-year university syllabi. It links to neighbouring topics Isotopes of nobelium, Lists of isotopes by element, Nobelium, so understanding it makes those chapters shorter.
In everyday life: Look for Isotopes of nobelium outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Isotopes of nobelium in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Isotopes of nobelium means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Isotopes of nobelium out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Isotopes of nobelium in simple terms?

Nobelium (102No) is a synthetic element, and thus a standard atomic weight cannot be given. Like all synthetic elements, it has no stable isotopes.

Why does Isotopes of nobelium matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Isotopes of nobelium?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Isotopes of nobelium.