Discovery
In 1957, a group of scientists at the Nobel Institute of Physics in Sweden used a cyclotron to bombard curium-244 atoms with carbon-13 ions, discovering a new element with a half-life of 10 minutes. In 1958, a research team at the University of California, Berkeley, consisting of John Walton, Thorburn Sicklen, Glenn Seaborg, and Albert Giorso, attempted to verify the former's discovery but failed to successfully prepare the isotope. However, the Berkeley team successfully prepared noreium-254 with a half-life of 3 seconds by bombarding curium-246 atoms with carbon-12 ions. A third research team at the Joint Institute for Nuclear Research in Russia also failed to reproduce the Nobel Institute's experimental results, but they confirmed the work of the Berkeley team. Therefore, noreium is ultimately considered to have been discovered by scientists from the University of California.
Physical properties
Nobelium is the next to last transuranic element of the actinide series. The transuranicelements are those of the actinide series that are heavier than uranium. Nobelium is also theheaviest element of the vertical group 16 (VIA).
Because it is only produced in minute quantities and its isotopes have such sort half-lives,not much is known about its properties. It melting point is known and is about 827°C, butits boiling point and density are unknown.
Isotopes
There a total of 15 isotopes of nobelium, ranging from 0.25 milliseconds (No-250) to 58 minutes (No-59). None are found in nature; all are unstable and are artificiallyproduced in cyclotrons.
Origin of Name
Named after the scientist Alfred Nobel, who invented dynamite and
used his fortune to fund and award the Nobel Prizes.
Occurrence
Nobelium does not exist in nature. All of its isotopes are radioactive with relatively shorthalf-lives. Some are unstable and spontaneously fission, and all of them are artificial and manmade.Small quantities of nobelium are produced in cyclotrons by bombarding curium-246with carbon-12 and neutrons to produce nobelium-254. The reaction follows:
96Cm-246 +
6C-12 →
102No-254. Carbon’s six neutron and six protons are accelerated to high-speeds ina cyclotron as they hit the curium atoms with great energy that produces an additional fourneutrons, thus producing the net gain in mass number by eight neutrons and an increase inatomic number by six protons, resulting in
102No-254.
Characteristics
Even though nobelium’s chemical and physical properties are unknown, it is reasonable toassume that they resemble 70Yb, which is located just above it in the lanthanide series.
History
Nobelium was
unambiguously discovered and identified in April 1958 at
Berkeley by A. Ghiorso, T. Sikkeland, J. R. Walton, and G. T.
Seaborg, who used a new double-recoil technique. A heavy-ion
linear accelerator (HILAC) was used to bombard a thin target
of curium (95%
244Cm and 4.5%
246Cm) with
12C ions to produce
102
254 according to the
246Cm (12C, 4n) reaction. Earlier in
1957 workers of the U.S., Britain, and Sweden announced the
discovery of an isotope of Element 102 with a 10-min half-life
at 8.5 MeV, as a result of bombarding 244Cm with 13C nuclei.
On the basis of this experiment the name nobelium was assigned
and accepted by the Commission on Atomic Weights
of the International Union of Pure and Applied Chemistry.
The acceptance of the name was premature, for both Russian
and American efforts now completely rule out the possibility
of any isotope of Element 102 having a half-life of 10 min in
the vicinity of 8.5 MeV. Early work in 1957 on the search for
this element, in Russia at the Kurchatov Institute, was marred
by the assignment of 8.9 ± 0.4 MeV alpha radiation with a halflife
of 2 to 40 sec, which was too indefinite to support claim
to discovery. Confirmatory experiments at Berkeley in 1966
have shown the existence of
254102 with a 55-s half-life,
252102
with a 2.3-s half-life, and 257102 with a 25-s half-life. Twelve
isotopes are now recognized, one of which —
255102 — has a
half-life of 3.1 min. In view of the discoverer’s traditional right
to name an element, the Berkeley group, in 1967, suggested
that the hastily given name nobelium, along with the symbol
No, be retained.
Uses
There are no uses for nobelium except for laboratory research.
Definition
A radioactive transuranic element of the actinoid series, not found naturally on Earth. Several very short-lived isotopes have been synthesized. Symbol: No; p.n. 102; most stable isotope
259No (half-life 58 minutes).
Definition
nobelium: Symbol No. A radioactivemetallic transuranic element belongingto the actinoids; a.n. 102; massnumber of most stable element 254(half-life 55 seconds). Seven isotopesare known. The element was firstidentified with certainty by AlbertGhiorso and Glenn Seaborg (1912–99)in 1966.
Definition
No. Synthetic radioactive element
number 102, aw 254, one of the actinide series
of elements; its discovery has been claimed by
research groups in Sweden, the former U.S.S.R.,
and California. It can be produced in a cyclotron
by bombarding copper with nuclei of carbon-13
accelerated to high energies. The name nobelium
has been accepted by the IUPAC Commission on
Nomenclature of Inorganic Chemistry. It has nine
isotopes (251–259) that are so short-lived that their
chemical properties have not been determined. It
has no known uses or compounds.
Hazard
Although nobelium poses a radiation hazard, the chances of being exposed to it are nil sincethere is little of it and its isotopes’ half-lives are only a few seconds and minutes.
Industrial uses
Element 102, called nobelium, has a halflifeof only 12 min. Other transuranic metalsproduced synthetically are americium (element95), and curium (element 96). Curium is usedas a heat source in remote applications. Curium244 is obtained as curium nitrate in the reprocessingof spent reactor fuel. It is converted tocurium oxide. The byproduct americium is usedas a component in neutron sources. Other transuranicmetals that have been produced bynuclear reactions and synthesis include fermium(element 100), mendelevium (element101), lawrencium (element 103), rutherfordiumor kurchatovium (element 104), and hahniumor nielsbohrium (element 105).
