A hard, silver gray metal belonging to the → platinum group of metals; symbol: Ru. It is found directly above osmium in Group 8 of the periodic table. → Atomic number 44, → atomic weight 101.07, → melting point about 2,310°C, → boiling point about 3,900°C, → specific gravity 12.41 at 20°C.
From L. ruthenia "Russia," because it was first found by the Russian chemist Gottfried Wilhelm Osann in 1828, despite not being recognized as an element. In 1844 the Russian chemist Karl Karlovich Klaus was able to isolate the ruthenium metal.
atom-e Rutherford (#)
Fr.: atome de Rutherford
A simple model assuming that the positive charge of the atom is not distributed uniformly throughout the atom (unlike the → Thomson atom), but is concentrated in a minute center or nucleus, and the negative charge is distributed over a sphere of radius comparable with the atomic radius.
After the British physicist and chesmist Ernest Rutherford (1871-1937), who put forward this model in 1911; Nobel Prize in Chemistry in 1908; → atom.
An artificially produced radioactive chemical element; symbol Rf. Atomic number 104; mass number of most stable isotope 261; melting point, boiling point, and specific gravity unknown. Rutherfordium was discovered in 1964 by a team of scientists at the Joint Institute for Nuclear Research at Dubna in Russia who named the element kurchatovium. The Russian scientists were unable to duplicate their results and therefore lost credit to a team of scientists at the University of California, Berkeley, who identified the element. The scientists in California were successful in isolating the element after irradiating 249Cf with 12C.
Named after the British physicist and chemist Ernest Rutherford (1871-1937), → Rutherford atom.
A unit of energy used in atomic physics, equal to about 13.6 electron-volts, the ionization potential of hydrogen.
In honor of the Swedish physicist Johannes Robert Rydberg (1854-1919), who did important contributions on spectroscopy, and in particular found a relatively simple expression relating the various lines in the spectra of chemical elements (1890).
pâyâ-ye Rydberg (#)
Fr.: constante de Rydberg
A fundamental constant of atomic physics appearing in the → Rydberg formula. The Rydberg constant for hydrogen is 109,739 cm-1.
Fr.: correction de Rydberg
A term inserted into a formula for the energy of a single electron in the outermost shell of an atom to take into account the failure of the inner electron shells to screen the nuclear charge completely.
Fr.: formule de Rydberg
A formula, used in atomic physics, which describes the wavelengths or frequencies of light in various series of related spectral lines, such as those emitted by hydrogen atoms.