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This is rutherfordium.

Symbol Rf
Atomic number 104
Atomic mass (261) amu

Rutherfordium is a radioactive, synthetic metal. In 1964, Soviet Nuclear Research reported the existence of 260Rf when a target of plutonium-242 is smashed with a very heavy ion of neon-22. At that time, the Lawrence Laboratory on the Berkeley campus of the University of California seems to have had difficulty reproducing the results. The American group was unable to accelerate neon ions, so they had to resort to a different procedure - bombarding californium-239 with carbon nuclei. The products of these reactions were 257Rf, 258Rf and 259Rf. By bombarding 248Cm with 18O, the American group were able to produce some 261Rf.

The Americans produced a wider variety of isotopes of element-104 and in quantities of thousands of atoms of each isotope instead of the Soviet's two or three. It appears that the Americans will be taking the honors for this discovery despite the Soviet's earlier announcement of the element. The American choice for a name of element-104 is Rutherfordium. This name is appearing in an ever-increasing amount of scientific literature.

See also

Periodic table of the elements