Mendelevium (also known as unnilunium, Unu) is a synthetic element in the periodic table with the symbol Md (formerly Mv) and the atomic number 101. A metallic radioactive transuranic element of the actinides, mendelevium is synthesized by bombarding einsteinium with alpha particles and was named after Dmitri Mendeleev.

Notable characteristics

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Researchers have shown that mendelevium has a moderately stable dipositive (II) oxidation state in addition to the more characteristic (for actinide elements) tripositive (III) oxidation state. ²⁵⁶Md has been used to find out some of the chemical properties of this element while in an aqueous solution. There are no other uses of mendelevium and only trace amounts of the element have ever been produced.

History

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Mendelevium (for Dmitri Mendeleyev, surname commonly spelt as Mendeleev, Mendeléef, or even Mendelejeff, and first name sometimes spelt as Dmitry or Dmitriy) was first synthesized by Albert Ghiorso (team leader), Glenn T. Seaborg, Bernard Harvey,Greg Choppin, and Stanley G. Thompson in early 1955. The team produced ²⁵⁶Md (half-life of 76 minutes) when they bombarded an ²⁵³Es target with alpha particles (helium nuclei) in the Berkeley Radiation Laboratory's 60-inch cyclotron (²⁵⁶Md was synthesized one-atom-at-a-time). Element 101 was the ninth transuranic element synthesized.

Isotopes

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15 radioisotopes of mendelevium have been characterized, with the most stable being ²⁵⁸Md with a half-life of 51.5 days, ²⁶⁰Md with a half-life of 31.8 days, and ²⁵⁷Md with a half-life of 5.52 hours. All of the remaining radioactive isotopes have half-lifes that are less than 97 minutes, and the majority of these have half-lifes that are less than 5 minutes. This element also has 1 meta state, ^258mMd (t_½ 57 minutes). The isotopes of mendelevium range in atomic weight from 245.091 amu (²⁴⁵Md) to 260.104 amu (²⁶⁰Md).

References

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• Los Alamos National Laboratory - Mendelevium
• Guide to the Elements - Revised Edition, Albert Stwertka, (Oxford University Press; 1998) ISBN 0-19-508083-1
• It's Elemental - Mendelevium

External links

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• WebElements.com - Mendelevium

Actinides | Chemical elements

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