Element (107)

Element 107, chemical element; for physical constants see Periodic Table. In 1976, Soviet scientists at the Joint Institute for Nuclear Research at Dubna (USSR) produced what they claimed was element 107 with mass number 261, by bombarding bismuth-204 with chromium-54. In 1981, Peter J. Armbruster and his co-workers in West Germany at the Heavy Ion Research Laboratory (GSI) at Darmstadt produced element 107 with mass number 262 by bombarding bismuth-209 with chromium-54 nuclei as well. The recoiling product atom was separated by a newly developed velocity filter. The new element decayed by three consecutive alpha-particle emissions to element 105 in 165 ms to lawrencium in 1.2 sec. and to mendelevium in 18.1 sec. It then became fermium by electron capture and emitted an alpha-particle to become californium.