nobelium

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 102²⁵⁴ 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).