|Atomic Number:||109||Atomic Radius:||empirical: 128 pm (predicted)|
|Atomic Symbol:||Mt||Melting Point:||—|
|Atomic Weight:||278||Boiling Point:||—|
|Electron Configuration:||[Rn]7s25f146d7 (calculated)||Oxidation States:||9, 8, 6, 4, 3, 1 (predicted)|
On August 29, 1982, physicists at the Heavy Ion Research Laboratory, Darmstadt, West Germany made and identified element 109 by bombing a target of 209Bi with accelerated nuclei of 58Fe. 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 262/107X. This in turn emitted an alpha particle, becoming 258/105Db, 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.