Nobelium
Encyclopedia
Nobelium is a synthetic element
with the symbol No and atomic number
102. It was first correctly identified in 1966 by scientists at the Flerov Laboratory of Nuclear Reactions in Dubna
, Soviet Union
. Little is known about the element but limited chemical experiments have shown that it forms a stable divalent ion in solution as well as the predicted trivalent ion that is associated with its presence as one of the actinoids.
in 1957. The team reported that they created an isotope with a half-life
of 10 minutes, decaying by emission of an 8.5 MeV
alpha particle, after bombarding 244Cm with 13C nuclei. The activity was assigned to 251No or 253No. The scientists proposed the name nobelium (No) for the new element. Later they retracted their claim and associated the activity to background effects.
The synthesis of element 102 was then claimed in April 1958 at the University of California, Berkeley
by Albert Ghiorso
, Glenn T. Seaborg
, John R. Walton and Torbjørn Sikkeland. The team used the new heavy-ion
linear accelerator (HILAC) to bombard a curium
target (95% 244Cm
and 5% 246Cm) with 13C
and 12C ions. They were unable to confirm the 8.5 MeV activity claimed by the Swedes but were instead able to detect decays from 250Fm, supposedly the daughter of 254102, which had an apparent half-life
of ~3 s.
In 1959 the team continued their studies and claimed that they were able to produce an isotope that decayed predominantly by emission of an 8.3 MeV alpha particle, with a half-life
of 3 s with an associated 30% spontaneous fission
branch. The activity was initially assigned to 254No but later changed to 252No. The Berkeley team decided to adopt the name nobelium for the element.
Further work in 1961 on the attempted synthesis of element 103
produced evidence for a Z=102 alpha activity decaying by emission of an 8.2 MeV particle with a half-life
of 15 s, and assigned to 255No.
Following initial work between 1958–1964, in 1966, a team at the Flerov Laboratory of Nuclear Reactions (FLNR) reported that they had been able to detect 250Fm from the decay of a parent nucleus (254No) with a half-life
of ~50s, in contradiction to the Berkeley claim. Furthermore, they were able to show that the parent decayed by emission of 8.1 MeV alpha particles with a half-life
of ~35 s.
In 1969, the Dubna team carried out chemical experiments on element 102 and concluded that it behaved as the heavier homologue of ytterbium
. The Russian scientists proposed the name joliotium
(Jo) for the new element.
Later work in 1967 at Berkeley and 1971 at Oak Ridge fully confirmed the discovery of element 102 and clarified earlier observations.
In 1992, the IUPAC-IUPAP Transfermium Working Group (TWG) assessed the claims of discovery and concluded that only the Dubna work from 1966 correctly detected and assigned decays to Z=102 nuclei at the time. The Dubna team are therefore officially recognised as the discoverers of nobelium although it is possible that it was detected at Berkeley in 1959.
The International Union of Pure and Applied Chemistry (IUPAC) officially recognised the name nobelium following the Berkeley results.
In 1994, and subsequently in 1997, the IUPAC ratified the name nobelium (No) for the element on the basis that it had become entrenched in the literature over the course of 30 years and that Alfred Nobel
should be commemorated in this fashion.
lic. If sufficient amounts of nobelium were produced, it would pose a radiation
hazard.
Some sources quote a melting point of 827 °C for nobelium but this cannot be substantiated from an official source and seems implausible regarding the requirements of such a measurement. However, the 1st, 2nd and 3rd ionization energies have been measured. In addition, an electronegativity value of 1.3 is also sometimes quoted. This is most definitely only an estimate since a true value can only be determined using a chemical compound of the element and no such compounds exist for nobelium.
of 58 minutes. Longer half-lives are expected for the as-yet-unknown 261No and 263No. An isomeric level has been found in 253No and K-isomers have been found in 250No, 252No and 254No to date.
The study of K-isomerism was recently studied by physicists at the University of Jyväskylä
physics laboratory (JYFL). They were able to confirm a previously reported K-isomer and detected a second K-isomer. They assigned spins
and parities of 8- and 16+ to the two K-isomers.
253No
In 1971, Bemis et al. was able to determine an isomeric level decaying with a half-life
of 31 µs from the decay of 257Rf. This was confirmed in 2003 at the GSI by also studying the decay of 257Rf. Further support in the same year from the FLNR appeared with a slightly higher half-life
of 43.5 µs, decaying by M2 gamma emission to the ground state.
252No
In a recent study by the GSI into K-isomerism in even-even isotopes, a K-isomer with a half-life
of 110 ms was detected for 252No. A spin
and parity
of 8- was assigned to the isomer.
250No
In 2003, scientists at the FLNR reported that they had been able to synthesise 249No which decayed by SF with a half-life
of 54µs. Further work in 2006 by scientists at the ANL showed that the activity was actually due to a K-isomer in 250No. The ground state isomer was also detected with a very short half-life
of 3.7µs.
Synthetic element
In chemistry, a synthetic element is a chemical element that is too unstable to occur naturally on Earth, and therefore has to be created artificially. So far 30 synthetic elements have been discovered—that is, synthesized...
with the symbol No and atomic number
Atomic number
In chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...
102. It was first correctly identified in 1966 by scientists at the Flerov Laboratory of Nuclear Reactions in Dubna
Dubna
Dubna is a town in Moscow Oblast, Russia. It has a status of naukograd , being home to the Joint Institute for Nuclear Research, an international nuclear physics research centre and one of the largest scientific foundations in the country. It is also home to MKB Raduga, a defence aerospace company...
, Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
. Little is known about the element but limited chemical experiments have shown that it forms a stable divalent ion in solution as well as the predicted trivalent ion that is associated with its presence as one of the actinoids.
Discovery profile
The discovery of element 102 was first announced by physicists at the Nobel Institute in SwedenSweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
in 1957. The team reported that they created an isotope with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 10 minutes, decaying by emission of an 8.5 MeV
MEV
MeV and meV are multiples and submultiples of the electron volt unit referring to 1,000,000 eV and 0.001 eV, respectively.Mev or MEV may refer to:In entertainment:* Musica Elettronica Viva, an Italian musical group...
alpha particle, after bombarding 244Cm with 13C nuclei. The activity was assigned to 251No or 253No. The scientists proposed the name nobelium (No) for the new element. Later they retracted their claim and associated the activity to background effects.
The synthesis of element 102 was then claimed in April 1958 at the University of California, Berkeley
University of California, Berkeley
The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...
by Albert Ghiorso
Albert Ghiorso
Albert Ghiorso was an American nuclear scientist and co-discoverer of a record 12 chemical elements on the periodic table. His research career spanned five decades, from the early 1940s to the late 1990s.-Early life:...
, Glenn T. Seaborg
Glenn T. Seaborg
Glenn Theodore Seaborg was an American scientist who won the 1951 Nobel Prize in Chemistry for "discoveries in the chemistry of the transuranium elements", contributed to the discovery and isolation of ten elements, and developed the actinide concept, which led to the current arrangement of the...
, John R. Walton and Torbjørn Sikkeland. The team used the new heavy-ion
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
linear accelerator (HILAC) to bombard a curium
Curium
Curium is a synthetic chemical element with the symbol Cm and atomic number 96. This radioactive transuranic element of the actinide series was named after Marie Skłodowska-Curie and her husband Pierre Curie. Curium was first intentionally produced and identified in summer 1944 by the group of...
target (95% 244Cm
Curium
Curium is a synthetic chemical element with the symbol Cm and atomic number 96. This radioactive transuranic element of the actinide series was named after Marie Skłodowska-Curie and her husband Pierre Curie. Curium was first intentionally produced and identified in summer 1944 by the group of...
and 5% 246Cm) with 13C
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
and 12C ions. They were unable to confirm the 8.5 MeV activity claimed by the Swedes but were instead able to detect decays from 250Fm, supposedly the daughter of 254102, which had an apparent half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of ~3 s.
In 1959 the team continued their studies and claimed that they were able to produce an isotope that decayed predominantly by emission of an 8.3 MeV alpha particle, with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 3 s with an associated 30% spontaneous fission
Spontaneous fission
Spontaneous fission is a form of radioactive decay characteristic of very heavy isotopes. Because the nuclear binding energy reaches a maximum at a nuclear mass greater than about 60 atomic mass units , spontaneous breakdown into smaller nuclei and single particles becomes possible at heavier masses...
branch. The activity was initially assigned to 254No but later changed to 252No. The Berkeley team decided to adopt the name nobelium for the element.
- + → → + 4
Further work in 1961 on the attempted synthesis of element 103
Lawrencium
Lawrencium is a radioactive synthetic chemical element with the symbol Lr and atomic number 103. In the periodic table of the elements, it is a period 7 d-block element and the last element of actinide series...
produced evidence for a Z=102 alpha activity decaying by emission of an 8.2 MeV particle with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 15 s, and assigned to 255No.
Following initial work between 1958–1964, in 1966, a team at the Flerov Laboratory of Nuclear Reactions (FLNR) reported that they had been able to detect 250Fm from the decay of a parent nucleus (254No) with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of ~50s, in contradiction to the Berkeley claim. Furthermore, they were able to show that the parent decayed by emission of 8.1 MeV alpha particles with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of ~35 s.
- + → → + 6
In 1969, the Dubna team carried out chemical experiments on element 102 and concluded that it behaved as the heavier homologue of ytterbium
Ytterbium
Ytterbium is a chemical element with the symbol Yb and atomic number 70. A soft silvery metallic element, ytterbium is a rare earth element of the lanthanide series and is found in the minerals gadolinite, monazite, and xenotime. The element is sometimes associated with yttrium or other related...
. The Russian scientists proposed the name joliotium
Frédéric Joliot-Curie
Jean Frédéric Joliot-Curie , born Jean Frédéric Joliot, was a French physicist and Nobel laureate.-Early years:...
(Jo) for the new element.
Later work in 1967 at Berkeley and 1971 at Oak Ridge fully confirmed the discovery of element 102 and clarified earlier observations.
In 1992, the IUPAC-IUPAP Transfermium Working Group (TWG) assessed the claims of discovery and concluded that only the Dubna work from 1966 correctly detected and assigned decays to Z=102 nuclei at the time. The Dubna team are therefore officially recognised as the discoverers of nobelium although it is possible that it was detected at Berkeley in 1959.
Naming
Element 102 was first named nobelium (No) by its claimed discoverers in 1957 by scientists at the Nobel Institute in Sweden. The name was later adopted by Berkeley scientists who claimed its discovery in 1959.The International Union of Pure and Applied Chemistry (IUPAC) officially recognised the name nobelium following the Berkeley results.
In 1994, and subsequently in 1997, the IUPAC ratified the name nobelium (No) for the element on the basis that it had become entrenched in the literature over the course of 30 years and that Alfred Nobel
Alfred Nobel
Alfred Bernhard Nobel was a Swedish chemist, engineer, innovator, and armaments manufacturer. He is the inventor of dynamite. Nobel also owned Bofors, which he had redirected from its previous role as primarily an iron and steel producer to a major manufacturer of cannon and other armaments...
should be commemorated in this fashion.
Physical properties
The appearance of this element is unknown, however it is most likely silvery-white or gray and metalMetal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
lic. If sufficient amounts of nobelium were produced, it would pose a radiation
Ionizing radiation
Ionizing radiation is radiation composed of particles that individually have sufficient energy to remove an electron from an atom or molecule. This ionization produces free radicals, which are atoms or molecules containing unpaired electrons...
hazard.
Some sources quote a melting point of 827 °C for nobelium but this cannot be substantiated from an official source and seems implausible regarding the requirements of such a measurement. However, the 1st, 2nd and 3rd ionization energies have been measured. In addition, an electronegativity value of 1.3 is also sometimes quoted. This is most definitely only an estimate since a true value can only be determined using a chemical compound of the element and no such compounds exist for nobelium.
Aqueous phase chemistry
First experiments involving nobelium assumed that it predominantly formed a +III state like earlier actinoids. However, it was later found that nobelium forms a stable +II state in solution, although it can be oxidised to an oxidising +III state. A reduction potential of −1.78 V has been measured for the No3+ ion. The hexaaquanobelium(II) ion has been determined to have an ionic radius of 110 pm.Summary of compounds and (complex) ions
| Formula | Names(s) |
|---|---|
| [No(H2O)6]3+ | hexaaquanobelium(III) |
| [No(H2O)6]2+ | hexaaquanobelium(II) |
Isotopes
Twelve radioisotopes of nobelium have been characterized, with the most stable being 259No with a half-lifeHalf-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 58 minutes. Longer half-lives are expected for the as-yet-unknown 261No and 263No. An isomeric level has been found in 253No and K-isomers have been found in 250No, 252No and 254No to date.
Synthesis of isotopes as decay products
Isotopes of nobelium have also been identified in the decay of heavier elements. Observations to date are summarised in the table below:| Evaporation Residue | Observed No isotope |
|---|---|
| 262Lr | 262No |
| 269Hs, 265Sg, 261Rf | 257No |
| 267Hs, 263Sg, 259Rf | 255No |
| 254Lr | 254No |
| 261Sg, 257Rf | 253No |
| 264Hs, 260Sg, 256Rf | 252No |
| 255Rf | 251No |
Chronology of isotope discovery
| Isotope | Year discovered | Discovery reaction |
|---|---|---|
| 250Nom | 2001 | 204Pb(48Ca,2n) |
| 250Nog | 2006 | 204Pb(48Ca,2n) |
| 251No | 1967 | 244Cm(12C,5n) |
| 252Nog | 1959 | 244Cm(12C,4n) |
| 252Nom | ~2002 | 206Pb(48Ca,2n) |
| 253Nog | 1967 | 242Pu(16O,5n),239Pu(18O,4n) |
| 253Nom | 1971 | 249Cf(12C,4n) |
| 254Nog | 1966 | 243Am(15N,4n) |
| 254Nom1 | 1967? | 246Cm(13C,5n),246Cm(12C,4n) |
| 254Nom2 | ~2003 | 208Pb(48Ca,2n) |
| 255No | 1967 | 246Cm(13C,4n),248Cm(12C,5n) |
| 256No | 1967 | 248Cm(12C,4n),248Cm(13C,5n) |
| 257No | 1961? , 1967 | 248Cm(13C,4n) |
| 258No | 1967 | 248Cm(13C,3n) |
| 259No | 1973 | 248Cm(18O,α3n) |
| 260No | ? | 254Es + 22Ne,18O,13C - transfer |
| 261No | unknown | |
| 262No | 1988 | 254Es + 22Ne - transfer (EC of 262Lr) |
Isomerism in nobelium nuclides
254NoThe study of K-isomerism was recently studied by physicists at the University of Jyväskylä
University of Jyväskylä
The University of Jyväskylä is a university in Jyväskylä, Finland. It has its origins in the first Finnish-speaking teacher training college , founded in 1863. Around 14,000 students are currently enrolled in the degree programs of the university...
physics laboratory (JYFL). They were able to confirm a previously reported K-isomer and detected a second K-isomer. They assigned spins
Spin (physics)
In quantum mechanics and particle physics, spin is a fundamental characteristic property of elementary particles, composite particles , and atomic nuclei.It is worth noting that the intrinsic property of subatomic particles called spin and discussed in this article, is related in some small ways,...
and parities of 8- and 16+ to the two K-isomers.
253No
In 1971, Bemis et al. was able to determine an isomeric level decaying with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 31 µs from the decay of 257Rf. This was confirmed in 2003 at the GSI by also studying the decay of 257Rf. Further support in the same year from the FLNR appeared with a slightly higher half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 43.5 µs, decaying by M2 gamma emission to the ground state.
252No
In a recent study by the GSI into K-isomerism in even-even isotopes, a K-isomer with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 110 ms was detected for 252No. A spin
Spin (physics)
In quantum mechanics and particle physics, spin is a fundamental characteristic property of elementary particles, composite particles , and atomic nuclei.It is worth noting that the intrinsic property of subatomic particles called spin and discussed in this article, is related in some small ways,...
and parity
Parity (physics)
In physics, a parity transformation is the flip in the sign of one spatial coordinate. In three dimensions, it is also commonly described by the simultaneous flip in the sign of all three spatial coordinates:...
of 8- was assigned to the isomer.
250No
In 2003, scientists at the FLNR reported that they had been able to synthesise 249No which decayed by SF with a half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 54µs. Further work in 2006 by scientists at the ANL showed that the activity was actually due to a K-isomer in 250No. The ground state isomer was also detected with a very short half-life
Half-life
Half-life, abbreviated t½, is the period of time it takes for the amount of a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms , but it may apply to any quantity which follows a set-rate decay.The original term, dating to...
of 3.7µs.
Cold fusion
The table below provides cross-sections and excitation energies for cold fusion reactions producing nobelium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel.| Projectile | Target | CN | 1n | 2n | 3n | 4n |
|---|---|---|---|---|---|---|
| 48Ca | 208Pb | 256No | 254No: 2050 nb ; 22.3 MeV | |||
| 48Ca | 207Pb | 255No | 253No: 1310 nb ; 22.4 MeV | |||
| 48Ca | 206Pb | 254No | 253No: 58 nb ; 23.6 MeV | 252No: 515 nb ; 23.3 MeV | 251No: 30 nb ; 30.7 MeV | 250No: 260 pb ; 43.9 MeV |
| 48Ca | 204Pb | 252No | 250No:13.2 nb ; 23.2 MeV |
Hot fusion
The table below provides cross-sections and excitation energies for hot fusion reactions producing nobelium isotopes directly. Data in bold represents maxima derived from excitation function measurements. + represents an observed exit channel.| Projectile | Target | CN | 3n | 4n | 5n | 6n |
|---|---|---|---|---|---|---|
| 26Mg | 232Th | 258No | 254No:1.6 nb | 253No:9 nb | 252No:8 nb | |
| 22Ne | 238U | 260No | 256No:40 nb | 255No:200 nb | 254No:15 nb | |
| 22Ne | 236U | 258No | 254No:7 nb | 253No:25 nb | 252No:15 nb |