from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A synthetic transuranic radioactive element having 9 isotopes with mass numbers from 243 to 250 and half-lives from 3 hours to 1,380 years. Atomic number 97; melting point 986°C; valence 3, 4. See Table at element.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A transuranic chemical element (symbol Bk) with an atomic number of 97.
from the GNU version of the Collaborative International Dictionary of English
- n. a chemical element of the transuranic series. Chemical symbol Bk; atomic number 97; atomic weight 247. It is a radioactive element, with no stable isotopes; the longest-lived isotope is of mass number 247.07, decaying by alpha-emission with a half-life of 1,400 years. The isotope with atomic weight 249 has a half-life of 314 days, and was isolated in weighable quantities.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a radioactive transuranic element; discovered by bombarding americium with helium
A team from the US and Russia produced the elusive element 117 by fusing together atoms of calcium and another rare, heavy element known as berkelium, filling in the final gap on the list of observed elements up to 118.
The team produced six atoms of the element by smashing together isotopes of calcium and a radioactive element called berkelium in a particle accelerator about 75 miles north of Moscow on the Volga River, according to a paper that has been accepted for publication at the journal
The team produced six atoms of the element by smashing together isotopes of calcium and a radioactive element called berkelium in a particle accelerator about 75 miles north of Moscow on the Volga River, according to a paper that has been accepted for publication at the journal Physical Review Letters.
The person who discovers the element gets to name it, which is why there are elements called berkelium and californium - for a while, UC Berkeley was the place to be for element hunters.
The two transuranium elements most recently discovered, berkelium and californium, correspond to terbium and dysprosium in the lanthanides.
Because calcium contains 20 protons, simple math indicates that scientists would have to fire the calcium at something with 97 protons - berkelium - in order to produce ununseptium, element 117.
The Russians collaborated with U.S. researchers, including some from Oak Ridge National Laboratory in Tennessee, where the berkelium target was made.
Berkelium happens to be mighty hard to come by, but a research nuclear reactor at Oak Ridge produced about 20 milligrams of highly purified berkelium and sent it to Russia, where the substance was bombarded for five months late last year and early this year.
After smashing calcium atoms into a target of berkelium in a particle accelerator at the Joint Institute for Nuclear Research in Dubna, Russia, the team deduced fleeting existence of element 117 by studying the daughter particles emitted as the atom decayed.
A team of American and Russian scientists produced six atoms of the elusive element in a particle accelerator, by smashing calcium atoms with another rare, heavy element known as berkelium.