Mendelevium

Mendelevium a synthetic element with the symbol **Md** (formerly **Mv**) and the atomic number 101. A metallic radioactive transuranic element in the actinide series, mendelevium is usually synthesized by bombarding einsteinium with alpha particles. It was named after Dmitri Ivanovich Mendeleev, who created the Periodic Table. Mendeleev's periodic system is the fundamental way to classify all the chemical elements. The name "mendelevium" was accepted by the International Union of Pure and Applied Chemistry (IUPAC). On the other hand, the proposed symbol "Mv" submitted by the discoverers was not accepted, and IUPAC changed the symbol to "Md" in 1963


 * Name:** Mendelevium
 * Symbol:** Md
 * Atomic Number:** 101
 * Atomic Mass:** (258.0) amu
 * Melting Point:** Unknown
 * Boiling Point:** Unknown
 * Number of Protons/Electrons:** 101
 * Number of Neut****rons:** 157
 * Classification:** Rare Earth
 * Crystal Structure:** Unknown
 * Density @ 293 K:** Unknown
 * Color:** Unknown


 * Date of Discovery:** 1955
 * Discoverer:** G.T. Seaborg
 * Name Origin:** After Dmitri Ivanovitch Mendeleyev
 * Uses:** No uses known
 * Obtained From:** Man-made


 * Number of Energy Levels:** 7
 * First Energy Level:**2
 * Second Energy Level:**8
 * Third Energy Level:**18
 * Fourth Energy Level:**32
 * Fifth Energy Level:**31
 * Sixth Energy Level:**8
 * Seventh Energy Level:**2

Isotopes

 * ** Isotope ** || ** Half Life ** ||
 * Md-250 || 50.0 seconds ||

Mendelevium was first produced by Stanley G. Thompson, Glenn T. Seaborg, Bernard G. Harvey, Gregory R. Choppin and Albert Ghiorso working at the University of California, Berkeley, in 1955. They bombarded atoms of einsteinium-253 with helium ions using a device known as a cyclotron. This produced atoms of mendelevium-256, an isotope with a half-life of about 77 minutes, and a free neutron. Mendelevium's most stable isotope, mendelevium-258, has a half-life of about 51.5 days. It decays into einsteinium-254 through alpha decay or decays through spontaneous fission. Since only small amounts of mendelevium have ever been produced, it currently has no uses outside of basic scientific research.
 * What's in a name?** Named after the Russian chemist Dmitri Mendeleyev.
 * Say what?** Mendelevium is pronounced as **men-deh-LEE-vee-em**.
 * History and Uses:**
 * Estimated Crustal Abundance:** Not Applicable
 * Estimated Oceanic Abundance:** Not Applicable
 * Number of Stable Isotopes:** 0
 * Ionization Energy:** 6.58 eV
 * Oxidation States:** +3, +2

Harmful effects: Mendelevium is harmful due to its radioactivity. Characteristics: Mendelevium is a synthetic, highly radioactive metal and has only been produced in miniscule amounts. Mendelevium was the first element to be produced one atom at a time. Mendelevium metal has not been prepared. (3a)

Uses of Mendelevium
Mendelevium is of scientific research interest only.

Solution chemistry
Before the actual discovery of mendelevium, the trivalent state was the most stable one in aqueous solution. Accordingly, a similar chemical behavior to the other 3+ actinides and lanthanides was expected. The elution of Md just before Fm in the elution sequence of the trivalent actinides from the cation-exchange resin column, confirmed this prediction. Afterwards, Md in the form of insoluble hydroxides and fluorides that are quantitatively coprecipitated with trivalent lanthanides was found. The cation-exchange resin column as well as the HDEHP solvent extraction column elution date is consistent with a trivalent state for Md and an ionic radius smaller than Fm. An ionic radius of 0.0192 nm and a coordination number of 6 for Md3+ was predicted using empirical correlations. Using the known ionic radii for the trivalent rare earths and the linear correlation of log distribution coefficient with ionic radius, an average ionic radius of 0.089 nm was estimated for Md3+ and a heat of hydration of – (3654 ± 12) kJ/mol calculated using empirical models and the Born-Haber cycle. In reducing conditions, an anomalous chemical behavior of Md was found. Coprecipitation with BaSO4 and solvent extraction chromatography experiments using HDEHP were carried out in different reducing agents. These showed that Md3+ could easily be reduced to a stable Md2+ in aqueous solution. Mendelevium can also be reduced to the monovalent state in water-ethanol solutions. The cocrystallization of Md+ with salts of divalent ions is due to the formation of mixed crystals. For Md+, an ionic radius of 0.117 nm was found. The oxidation of Md3+ to Md4+ was rather unsuccessful.