nobelium

nobelium

a transuranic element produced artificially from curium. Symbol: No; atomic no.: 102; half-life of most stable isotope, ²⁵⁵No: 180 seconds (approx.); valency: 2 or 3

Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005

nobelium

[nō′bel·ē·əm]

(chemistry)

A chemical element, symbol No, atomic number 102; a synthetic element, in the actinium series; isotopes with mass numbers 250-260 and 262 have been produced in the laboratory, with mass number 259 having the longest known half-life, 58 minutes.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Nobelium

 

No (element 102), an artificially produced radioactive chemical element of the actinide family, with atomic number 102.

The preparation of atoms of element 102 was first announced in 1957 by an international group of scientists working in Stockholm, Sweden, that also proposed that the element be named in honor of A. Nobel, the founder of a fund for international prizes (Nobel Prizes). However, subsequent experiments conducted at Berkeley (USA) and the Joint Institute for Atomic Studies (Dubna, USSR) showed that the conclusion of the Stockholm group was erroneous.

The first reliable information on isotopes of element 102 with mass numbers 251–256 was obtained during the period from 1963 to 1967 by a group of Soviet physicists at Dubna, headed by G. N. Flerov. For the synthesis of these isotopes the Soviet group irradiated nuclei of isotopes of uranium, plutonium, and americium with accelerated ions of neon, oxygen, and nitrogen. The results of the Dubna group have been fully confirmed. The Soviet scientists have proposed naming element 102 joliotium (symbol Jl) in honor of Jean Frédéric Joliot-Curie. As yet there is no commonly accepted name for element 102.

As of 1974, isotopes of nobelium with mass numbers from 251 to 259 had been obtained in microscopic quantities. The most long-lived isotope, ²⁵⁹102 (half-life, about 1.5 hr), was synthesized in 1970 at Oak Ridge (USA). The first chemical identification of element 102 was carried out by a group of Flerov’s colleagues using a technique developed for studying kurcha-tovium. The volatility of the chloride of element 102 is similar to that of the chlorides of fermium and californium. The most stable oxidation state of nobelium in solution is + 2; it may pass into an oxidation state of + 3 under the action of strong oxidizing agents.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.