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Mendelevium is an exclusively artificially produced chemical element with the element symbol Md and the atomic number 101 In the periodic table it is in the group of actinides (7th period, f - block), and also one of the transuranic elements. Mendelevium is a radioactive metal that but have not been shown as a metal due to the limited quantities available. It was discovered in 1955 and named after the Russian chemist and inventor of the Periodic Table Dmitri Mendeleev. The name was finally confirmed in 1994 by the IUPAC.


Mendelevium 1955 was generated for the first time at the University of California at Berkeley by Stanley G. Thompson, Albert Ghiorso, Bernard G. Harvey, Gregory Choppin and Glenn T. Seaborg. The discoverers suggested this name in honor of Mendeleev before, just as the abbreviation Mv. The IUPAC decided to use the name, but with the symbol Md.

To produce a 253Es target was bombarded in a cyclotron with accelerated α - particles. This creates 256Md and a free neutron.

Later, the element was temporarily designated by the systematic name Unnilunium.


In the periodic table is the Mendelevium with the atomic number 101 in the series of actinides, its predecessor is the fermium, the subsequent element is the nobelium. Its analogue in the series of lanthanides is the thulium.

Mendelevium is a radioactive and very short-lived metal. The most stable isotope of Mendelevium is 258Md with a half-life of about 51.5 days. It decays by alpha decay to 254Es. In monovalent form, it has not been observed.


Classifications according to the Hazardous Substances Ordinance are not available because they only include the chemical danger and play a very minor role compared to the risks based on the radioactivity. Even the latter applies only if there is a relevant material for this amount.