Hassium

Hassium

Proposed Name

History

(origin is Latin "Hassias" meaning "Hess", the German state.) Discovered by Peter Armbruster, Gottfried Munzenber and co-workers at GSI in Darmstadt, Germany in 1984.

Sources: CRC Handbook of Chemistry and Physics and the American Chemical Society.

Last Updated: 12/19/97, CST Information Services Team

http://pearl1.lanl.gov/periodic/elements/108.html [3/6/2001 8:38:21 AM]

Meitnerium

Meitnerium

Proposed Name

History

On August 29, 1982, physicists at the Heavy Ion Research Laboratory, Darmstadt, West Germany made and identified element 109 by bombing a target of Bi-209 with accelerated nuclei of Fe-58. If the combined energy of two nuclei is sufficiently high, the repulsive forces between the nuclei can be overcome.

In this experiment a week of target bombardment was required to produce a single fused nucleus. The team confirmed the existence of element 109 by four independent measurements. The newly formed atom recoiled from the target at predicted velocity and was separated from smaller, faster nuclei by a newly developed velocity filter. The time of flight to the detector and the striking energy were measured and found to match predicted values.

The nucleus of 266X started to decay 5 ms after striking the detector. A high-energy alpha particle was emitted, producing 267/107X. This in turn emitted an alpha particle, becoming 258/105Ha, which in turn captured an electron and became 258/104Rf. This in turn decayed into other nuclides. This experiment demonstrated the feasibility of using fusion techniques as a method of making new, heavy nuclei.

Sources: CRC Handbook of Chemistry and Physics and the American Chemical Society.

Last Updated: 12/19/97, CST Information Services Team

http://pearl1.lanl.gov/periodic/elements/109.html [3/6/2001 8:38:21 AM]

Element 110

Element 110

Unnamed

Press Release:Discovery of Element 110 at GSI

November 9, 1994 at 4:39 pm, the first atom of the heaviest chemical atom with atomic number 110 was detected at the Gesellschaft fur Schwerionenforschung (GSI) in Darmstadt, in Germany. For the last ten years, this element has been the subject of an intense search by many laboratories world-wide.

Discovery

Element 110 was produced by fusing nickel and lead atom together. This was achieved by accelerating the nickel atoms to a high energy in the heavy ion accelerator. "This rare reaction occurs only at a very specific velocity of the nickel projectile. Over a period of many days, many billion billion nickel atoms must be shot at a lead target in order to produce and identify a single atom of element 110. The atoms produced in the nickel-lead collisions are selected by a velocity filter and then captured in a detector system which measures their decay. The energy of the emitted helium nuclei serves to identify the atom" (Press Release). This element was only found to have a lifetime of less than 1/1000th of a second. It is expected that soon a heavier version of element 110 that might be more stable, and that lives slightly longer will be developed.

Sources: Element 110 Discovered and the GSI.

Last Updated: 12/19/97 CST Information Services Team

http://pearl1.lanl.gov/periodic/elements/110.html [3/6/2001 8:38:21 AM]

Element 111

Element 111

History

Discovered by Gesellschaft Schwerionenforschung (GSI) in Darmstadt, in 1994. Reasearch group of S. Hofmann, V. Ninov, F.P. Hessberger, P. Armbruster, H. Folger, G. Munzenberg, H.J. Schott, and others.

Sources: CRC Handbook of Chemistry and Physics and the American Chemical Society.

Last Updated: 12/19/97, CST Information Services Team

http://pearl1.lanl.gov/periodic/elements/111.html [3/6/2001 8:38:21 AM]