Mallika (Mulliken), Robert S.

June 7, 1896, Mr.. - October 31, 1986
The American chemist Robert Mulliken Sander-son was born in Newburyport (Mass.), the son of Samuel Parsons Mulliken, professor of organic chemistry at MIT, and Catherine (Uilmart) Mulliken. M. showed interest in the molecular structure, . even when he was in high school, . where he was to deliver a report at the end of the school bore the name is quite typical: 'Electron: what it is and how he behaves' ( 'The Electron: What It Is and What It Does'),
. Received in 1917. the Massachusetts Institute of Technology Bachelor's degree in chemistry, M. within two years he worked at the U.S. Bureau of Mines, in the Army Chemical Defense and the 'New Jersey Zinc Company'. In 1919, Mr.. he entered graduate school in chemistry at the University of Chicago, and in 1921. received his doctorate in physical chemistry, with a thesis on the separation of isotopes of mercury by the method of fractional distillation. (Isotopes - a variety of one and the same chemical element, atomic nuclei which contain the same number of protons but different number of neutrons.) Scholarship National Research Council has allowed M. continue study of the behavior of isotopes in the Harvard. During his studies he became interested in the influence of the isotopes in the line spectrum of diatomic molecules.
. When the atoms come to an excited state (for example, temperature increases), they emit light in a characteristic spectrum, so that the lines of a specific color within a certain distance from each other
. Applying the provisions of the quantum theory developed by Max Planck and Albert Einstein in the first decade of XX century., Niels Bohr created the model of the atom in which electrons are 'allowed' only on the energy levels (orbitals). Spectral lines show the wavelengths of light energy emitted at a time when the electrons 'jump' from one allowed them to state to another.
. Molecules, the basic units of chemical compounds, also have a characteristic spectrum, more complex than the spectra of individual atoms
. Additional state of excitation in the molecule - sub-atomic vibration, molecular rotation and change of conformation - lead to the emission (emission) of energy with a broader range of wavelengths. Thus, the molecular spectrum consists of broad bands rather than lines.
Realizing that quantum theory is crucial to his work, M. in 1925. went to Europe to learn from leading physicists and specialists in spectroscopy. In 1926, Mr.. He returned to the U.S. as an assistant professor of physics Washington-SQUARE-College-CUNY. Erwin Schrodinger, Max Born and Werner Heisenberg had just published a detailed mathematical calculations in quantum field theory. They contained a formula that could be used to describe the behavior of electrons in atoms. Nevertheless, the electronic structure of molecules yield analysis with very great difficulty. In 1927, Mr.. MS, working with Friedrich Hund at Gottingen University in Germany, suggested that atoms combine into molecules in a process called formation of chemical bonds, so that their outer electrons are associated with the molecule as a whole. Consequently, the outer electrons in the molecules that determine many of its important properties are the molecular orbitals, rather than orbitals of individual atoms. M. proved that the molecular orbitals can be described by precise mathematical formulas, allowing you to predict significant detail physical and chemical properties of matter.
In 1928, Mr.. Moscow, already has received international recognition for his work, became an associate professor of physics at the University of Chicago, and in 1931. - Full professor. From 1957 to 1961. he was a professor emeritus of the University of Chicago.
In 1916, Mr.. Gilbert H. Lewis theoretical basis that the formation of chemical bonds is due to the formation of a common pair of electrons between atoms in a molecule. By Linus. Pauling and his colleagues, . Combining this concept with the provisions of quantum mechanics, . created the theory of chemical bond, . which very accurately describes the molecule, . having simple chemical bonds (bonds, . formed by one pair of electrons),
. However, this so-called theory of resonance is not suitable to describe the behavior of molecules with a more complex structure of the chemical bonds. The theory of resonance examines the socialization of electrons by atoms as a localized communication, in which each atom retains its fundamental electronic configuration. In molecules with multiple bonds socialized electrons occupy much larger volume, and between them there is a mutual repulsion, which can not be described in terms of localization of chemical bonds. M. failed to prove the superiority of his model of the formation of molecular chemical bonds in the analysis of complex molecules, as well as to establish the shape and relative energies of orbitals for many compounds.
M. continued to study the basic mechanisms of molecular structure, combining spectroscopic analysis of complex theoretical calculations. The invention of a universal computer scientists has provided a powerful tool, M. and his colleagues first created a computer program to decipher the molecular structure. During 50-ies. was attache on Science in embassy USA in London.
In 1966, Mr.. M. Nobel Prize on khimii 'per fundamental work on chemical Liaison and electronic structure molecules undertaken with using method molecular orbitals'. 'Method molecular orbitals means absolutely new understanding nature chemical ties, - said Inga Fischer-Dzhalmar in his introductory remarks behalf Swedish royal akademii nauk. - The earlier ideas came from the idea that ... formation of chemical bonds depends on the full interaction between the atoms. The method of molecular orbitals, on the contrary, relying on the provisions of quantum mechanics, is repelled by the interaction between all the atomic nuclei and all electrons of the molecule. This method has made extremely important contributions to our understanding of the qualitative aspect of the formation of chemical bonds and electronic structure of molecules'.
In addition to his work at the University of Chicago, M. many lectured. In 1960, Mr.. He has lectured at Cornell, and in 1965. - At Yale. Then, in 1965, M. was a visiting professor at the University of Amsterdam. After the official resignation in 1961,. he as professor emeritus of physics and chemistry continued to work in the University of Chicago. From 1965 to 1971. M. during the winter months, also held the position of Distinguished Professor of Chemical Physics, Florida State University.
In 1929, Mr.. M. married Mary Helen von Noah, daughter of the Austrian geologist, who immigrated to the United States, taught at the University of Chicago. In the couple had two daughters. M. described as unpretentious, good-natured man. He had a wide knowledge of botany, with pleasure drove the car, like oriental rugs, was fond of art. Died scientist October 31, 1986, Mr.. in Arlington (Virginia).
In addition to the Nobel Prize, M. was awarded the American Chemical Society Medal of Gilbert Newton Lewis (1960), Theodore William Richards Medal (1960), Peter Debye Award in Physical Chemistry (1963) and Willard Gibbs Medal (1965). He was a member of the U.S. National Academy of Sciences, the American Association for the Advancement of Science and the American Academy of Arts and Sciences and a foreign member of the Royal Society of London. M. were awarded honorary degrees from Columbia, Markettskogo, Cambridge and Stockholm University