Chemical Element: mendelevium

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Chemical-Element Information

Symbol: Md
Atomic number: 101
Year discovered: 1955

Discovered by: Albert Ghiorso (born July 15, 1915), Glenn Theodore Seaborg (1912-1999), American physicist, Bernard Harvey, Gregory Choppin, and Stanley G. Thompson.

• Mendeléyev, the ninth transuranium element of the actinide series to be discovered, was first identified by Seaborg and others in 1955 as a product of the bombardment of the einsteinium isotope with helium ions.
• Dmitri Ivanovich Mendeléyev (1834-1907) was a Russian chemist who arranged the chemical elements in the periodic table according to their atomic weights and predicted the existence of the elements gallium, scandium, and germanium before their discovery.
• He was born at Tobolsk, Siberia, on February 7 (new style; January 27, old style), 1834.
• In 1890, he resigned from his position as a professor and in 1893, he became the director of the bureau of weights and measures, a post which he occupied until his death at St. Pertersburg on February 2 (new style) or January 20 (old style), 1907.
• Mendeléyev's name, like that of Lothar Meyer, is best known for his work on the periodic law.
• Various chemists had traced numerical sequences among the atomic weights of some of the elements and noted connections between them and the properties of the different substances.
• Mendéleyev is given credit for developing a “full expression to the generalization, and to treat it not merely as a system of classifying the elements according to certain observed facts, but as a ‘law of nature’ which could be relied upon to predict new facts.” Encyclopedia Britannica.
• In 1871, he was led by certain gaps in his tables to assert the existence of three new elements so far unknown to the chemist and to assign them and their compounds definite properties.
• These three he called eka-boron, eka-aluminum, and eka-silicon.
• His prophecy was completely vindicated within 15 years by the discovery and study of gallium in 1875, scandium in 1879, and germanium in 1886.
• In several cases, he questioned the correctness of the “accepted atomic weights,” because he did not believe they complied with the periodic law, and here also, he was justified by subsequent investigation.

Name in other languages:

French: mendélévium

German: Mendelevium

Italian: mendelevio

Spanish: mendelevio

Information about other elements may be seen at this Chemical Elements List.

A special unit about words that include chemo-, chem- may be seen here.