Periodic Table -> Mendelevium


Mendelevium Details

Mendelevium Symbol: Md

Mendelevium Atomic Number: 101

Mendelevium Atomic Weight: (256)

What is Mendelevium?

Mendelevium (atomic number 101, symbol Md) is a radioactive and synthetic element in the actinide series. It is named after Dmitri Mendeleev, whose periodic system classifies all chemical elements. IUPAC or the International Union of Pure and Applied Chemistry accepted the name mendelevium.

The element has 16 isotopes with masses from 245 to 260. The most stable isotope is mendelevium-258, and it has a half-life of 51.5 days. The isotope decays into einsteinium-254 through spontaneous fission or alpha decay. Mendelevium-257 has a half-life of 5.52 hours and mendelevium-260 – a half-life of 31.8 days. The other radioactive isotopes of the element have half-lives of less than 97 minutes. Mendelevium has five meta states, and mendelevium-258 is the long-lived of them.

Mendelevium-256 has been used to study the chemical properties of mendelevium in an aqueous solution. The element itself was first synthesized by Stanley Thompson, Bernard Harvey, Gregory Choppin, Glenn Seaborg, and Albert Ghiorso at the University of California in 1955. The research team of Stanley Thompson produced mendelevium-256 with a half-life of 87 minutes. The team used helium nuclei (alpha particles) to bombard einsteinium-253 in a 60-inch cyclotron. Mendelevium-256 was the first isotope synthesized by the researchers – 1 atom at a time. The ion-exchange adsorption-elution technique was used to create and analyze the first 17 atoms of mendelevium. During the experiment, the element behaved like its homologue thulium.

In 1975, Rosengren and Johansson predicted that mendelevium, similar to ytterbium and europium, would prefer a divalent metallic state and not a trivalent state. Trace amounts of mendelevium were used in thermochromatographic studies to confirm that the element forms a divalent metal. The researchers estimated a divalent metallic radius.

To remove mendelevium atoms from the collector foil, dissolution of gold foil or thin etching was used. Mendelevium atoms can be isolated and purified using different techniques and from other products. Trivalent actinides can be separated from La carrier and lanthanide fission products using a 10 percent ethanol/ 90 percent water solution saturated with hydrochloric acid as eluant. Hydrochloric acid is used to separate mendelevium from the catcher foil. Actinides such as mendelevium pass through while gold remains on the column. Ammonium salts were used to treat a cation-exchange resin column as to separate fractions that contain elements 101, 100, and 99. The elusion position was used for the purpose of chemical identification (just before Fm).

The density and boiling point of the element are unknown. Its ionic radius and Vanderwaals radius are also unknown. Its melting point is at 1521 °F or 827 °C. There is no data on its magnetic ordering, and its appearance is unknown. A standard atomic mass is not available because mendelevium is a synthetic element. Similar to other synthetic elements, mendelevium does not have stable isotopes.

This element is classified as a metal, and it is solid at room temperature. Its oxidation states are +2 and +3, and its ionization energy is 6.58 eV. Its electron shell configuration has been confirmed.

Transferium elements do not have economic role or application. They have unstable nuclei and do not occur in nature. For this reason, they are quite difficult to detect or make. Mendelevium health hazards are not a source of concern given that it is not found in the earth’s crust.

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