Mendelevium
Atomic Number: 101
Atomic Symbol: Md
Atomic Weight: 258
Electron Configuration:[Rn]7s^2 5f^13History
(Dmitri Mendeleev) Mendelevium, the ninth transuranium element of the actinide series
discovered, was first identified by Ghiorso, Harvey, Choppin, Thompson, and Seaborg in early
in 1955 during the bombardment of the isotope 253Es with helium ions in the Berkeley 60-inch
cyclotron. The isotope produced was 256Md, which has a half-life of 76 min. This first
identification was notable in that 256Md was synthesized on a one-atom-at-a-time basis.
Isotopes
Fourteen isotopes are now recognized. 258Md has a half-life of 2 months. This isotope has been
produced by the bombardment of an isotope of einsteinium with ions of helium. Eventually
enough 258Md should be made to determine its physical properties.
Uses
256Md has been used to elucidate some of the chemical properties of mendelevium in aqueous
solution.
Properties
Experiments seem to show that the element possesses a moderately stable dipositive (II)
oxidation state in addition to the tripositive (III) oxidation state, which is characteristic of the
actinide elements.
Sources: CRC Handbook of Chemistry and Physics and the American Chemical Society.
Last Updated: 12/19/97, CST Information Services Team
Mendeleviumhttp://pearl1.lanl.gov/periodic/elements/101.html [5/17/2001 4:06:48 PM]