1s² 2s²p⁶ 3s²p⁶d¹⁰ 4s²p⁶d¹⁰f¹⁴ 5s²p⁶d¹⁰f¹³ 6s²p⁶ 7s²

History

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 G. Harvey, Gregory R. Choppin, and Stanley G. Thompson in early 1955 at the University of California, Berkeley.  They bombarded the isotope ²⁵³Es with helium ions (alpha particles) in the Berkeley 60-inch cyclotron, ejecting a neutron and yileding a nucleus of ²⁵⁶Md.   ²⁵⁶Md has a half-life of 78 minutes. This first identification was notable in that ²⁵⁶Md was synthesized on a one-atom-at-a-time basis.  The most stable isotope is ²⁵⁸Md with a half-life of 51.5 days.

Dimitri Mendeleev

Characteristics

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.

Applications

Since only small amounts of mendelevium have ever been produced, it currently has no uses outside of basic scientific research.

Isotopes

Eighteen radioisotopes of mendelevium have been characterized, with the most stable being ²⁵⁸Md.   ²⁵⁸Md produced by the bombardment of an isotope of einsteinium with ions of helium has a half-life of 51.5 days.  It decays into ²⁵⁴Es through alpha decay or decays through spontaneous fission.   ²⁶⁰Md has a half-life of 31.8 days and ²⁵⁷Md 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 245.08083 amu (²⁴⁵Md) to 262.10887 amu (²⁶²Md).  Eventually enough ²⁵⁸Md should be made to determine its physical properties.

Mendeleyev's 1872 Periodic Table