Meitnerium

	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 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 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.