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Meitnerium

Proposed Name

Atomic Number: 109
Atomic Symbol: Mt
Atomic Weight: 265
Electron Configuration: [Rn]7s25f146d7

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.





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