Meitnerium


Atomic Number: 109

Atomic Symbol: Mt

Atomic Weight: (266)

Electron Configuration: -32-15-2


On August 29, 1982, Element 109 was made and identified by physicists of the Heavy Ion Research Laboratory, Darmstadt, West Germany, 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 it took a week of target bombardment 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 separted 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 decays into other nuclides. This experiment demonstrated the feasibility of using fusion techniques as a method of making new, heavy nuclei.