|Atomic mass||(255) amu|
Nobelium was created in 1957. An international team of researchers from the United States, Great Britain, and Sweden announced the discovery of nobelium. It was created with a cyclotron at the Nobel Institute of Physics in Stockholm when a target of curium-244 was bombarded with heavy carbon-13 ions. The creation of element 102 has a half-life of 10 minutes.
In 1958, scientists from the Berkeley Lab in California set out to verify the results from the Nobel Institute but could not reproduce the findings of the Nobel group. The Berkeley radiation, who had been reporting discoveries of new elements for almost two decades, produced an isotope of the new element having an atomic mass of 254 and a half-life of 3 seconds. The claim to prior discovery was subsequently awarded to the Berkeley group.
Nobelium is near the end of the actinide series. It is a transuranium element because it is an element heavier than uranium. All known isotopes of nobelium are radioactive.