Mendelevium Facts – Element 101 or Md

Mendelevium is a radioactive metal.
Mendelevium is a radioactive metal.

Element Name: Mendelevium

Atomic Number: 101

Symbol: Md

Atomic Weight: 258.1

Discovery: G.T. Seaborg, S.G. Tompson, A. Ghiorso, K. Street Jr. (1955, United States)

Electron Configuration: [Rn] 7s2 5f13

Word Origin: Named in honor of Dmitri Mendeleev, who devised a periodic table of the elements

Isotopes: Fourteen isotopes have been recognized.

Properties: Mendelevium is the ninth transuranium element of the actinide series. Experiments indicate that mendelevium has a moderately stable dipositive (II) oxidation state in addition to the tripositive (III) oxidation state, as is characteristic of the actinide elements.

Uses: Md-256 has been used to determine some of the chemical properties of mendelevium in aqueous solution.

Sources: Mendelevium first was produced during the bombardment of Es-253 with helium ions in the Berkeley 60-inch cyclotron. The isotope produced was Md-256, with a half-life of 76 min. Md-256 was synthesized on a one-atom-at-a-time basis.

Element Classification: Radioactive Rare Earth Element (Actinide Series)

Melting Point (K): 1100

Appearance: Radioactive, synthetic metal

Atomic Radius (pm): 287

Pauling Negativity Number: 1.3

First Ionizing Energy (kJ/mol): (635)

Oxidation States: 3

References: Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange’s Handbook of Chemistry (1952), CRC Handbook of Chemistry & Physics (18th Ed.)