The Elements - Periodic Table

(Marvins-Underground-K-12) #1

Meitnerium


Proposed Name
Atomic Number: 109
Atomic Symbol: Mt
Atomic Weight: 265
Electron Configuration:[Rn]7s^2 5f^14 6d^7

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


Meitnerium

http://pearl1.lanl.gov/periodic/elements/109.html [5/17/2001 4:06:42 PM]
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