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ROALD HOFFMANN

Francis Cudjoe, group 2. Scientific adviser is Tatyana Tishakova.


Roald Hoffmann was born in Zloczów, July 18, 1937 poland (now ukraine) and named in honor of the Norwegian explorer, Roald Amundsen. His family immigrated to the United States of America in 1949, where he attended Stuyvesant High School, graduating in 1955. He received his bachelor of arts degree at Columbia University (Columbia College) in 1958, and his Master of Arts degree in 1960 and his Doctor of Philosophy degree (working under the subsequent 1976 chemistry Nobel Prize winner William N. Lipscomb, Jr.) in 1962, both from Harvard University.

He has investigated both organic and inorganic substances, developing computational tools and methods such as the extended Hückel method, which he proposed in 1963.

He is also a writer of poetry published in two collections, "The Metamict State" (1987) and "Gaps and Verges" (1990), and of books explaining chemistry to the general public. Also, he wrote a play called "O2 Oxygen" about the discovery of Oxygen, but also about what it means to be a scientist and the importance of process of discovery in science.

The Prizewinners work aims at theoretically anticipating the course of chemical reactions. It is based on quantum mechanics (the theory whose starting point is that the smallest building blocks of matter may be regarded both as particles and as waves), which attempts to explain how atoms behave. The Chemistry Prizewinners theories developed via close interaction with the empirical findings of experimental chemists. Hoffmann's first really powerful theoretical work carried out in 1965 in collaboration with R.B. Woodward at the University of Harvard. Woodward (died in 1979) was awarded the 1965 noble price in Chemistry for contributions of a completely different kind - for his outstanding achievements in building up complex organic molecules experimentally.

Good theoretical models provide guidance for experimental researchers and save them time. Fukui's and Hoffmann's theories are milestones in the development of our understanding of the course of chemical reactions. This development has, however, by no means been brought to a halt by the prizewinning work. This work has provided inspiration for new lines of development. Fukui and Hoffmann are among the most active researchers in these areas today.

He currently teaches at Cornell University in Ithaca, New York.



LEONOR MICHAELIS

Josefyn Nemi, group 2, Scientific adviser is Tatyana Tishakova.


Leonor Michaelis was born in Berlin, Germany on January 16, 1875 and graduated from the humanistic Koellnisches Gymnasium in 1893 after passing the Abiturienten Examen. During his time at Berlin University, Michaelis worked in the lab of Oskar Hertwig, even receiving prize for a paper on the histology of milk secretion. Michaelis’s doctoral thesis work on cleavage determination in frog eggs led him to write a textbook on embryology. Through his work at Hertwig’s lab, Michaelis came to know Paul Ehrlich and his work on blood cytology; he worked as Ehrlich’s private research assistant from 1898 to 1899.

He passed his physician’s examination in 1896 in Freiburg, and then moved to Berlin, where he received his doctorate in 1897. After receiving his medical degree, Michaelis worked as a private research assistant to Moritz Litten (1899–1902) and for Ernst Viktor von Leyden (1902–1906).

From 1900 to 1904, Michaelis continued his study of clinical medicine at a municipal hospital in Berlin, where he found time to establish a chemical laboratory. He attained the position of Privatdocent at the University of Berlin in 1903. In 1905 he accepted a position as director of the bacteriology lab in the city hospital "Am Urban", becoming Professor extraordinary at Berlin University in 1908. In 1914 he published a paper suggesting that Emil Abderhalden's notorious pregnancy tests could not be reproduced, a paper which fatally compromised Michaelis' position as an academic in Germany (L. Michaelis, L von Lagermark, Deutsche Med. Wochenschr. 1914, 7, 316-319). In 1922, Michaelis moved to the Medical School of the University of Nagoya (Japan)[2] as Professor of biochemistry, becoming one of the first foreign professors at a Japanese university, bringing with him several documents, apparatuses and chemicals from Germany.[3] His research in Japan focused on potentiometric measurements and the cellular membrane.

In 1926, he moved to Johns Hopkins University in Baltimore, Maryland as resident lecturer in medical research and in 1929 to the Rockefeller Institute of Medical Research inNew York City, where he retired in 1941.

Besides his role in the formulation of the famous Michaelis-Menten equation (1913) he discovered Janus green as a supravital stain for mitochondria and the Michaelis-Gutmann body in urinary tract infections (1902) and found that thioglycolic acid could dissolve keratin, a discovery that would come to have several implications in the cosmetic industry, including the permanent wave.

Leonor Michaelis died on October 8, 1949 in New York City.

Michaelis was a Harvey Lecturer in 1924 and a Sigma Xi Lecturer in 1946. He was elected to be a Fellow of the American Association for the Advancement of Science in 1929, a member of the National Academy of Sciences in 1943. In 1945, he received an honorary LL.D. from the University of California, Los Angeles.

JACOBUS HENRICUS VAN 'T HOFF

Asiedu nketia Emmanuel, group 2. Scientific adviser is Tatyana Tishakova.


Jacobus Henricus van 't Hoff (30 August 1852 – 1 March 1911) was a Dutch physical and organic chemist and the first winner of the Nobel Prize in Chemistry. He is best known for his discoveries in chemical kinetics, chemical equilibrium, osmotic pressure, and stereochemistry.

Before he received his doctorate, Van 't Hoff had already published the first of his important contributions to the field of organic chemistry. In 1874 he accounted for the phenomenon of optical activity by assuming that the chemical bonds between carbon atoms and their neighbors were directed towards the corners of a regular tetrahedron. This three-dimensional structure accounted for the isomers found in nature.

Van 't Hoff published his work on stereochemistry in his book La chimie dans l'espace in 1874. In 1884, Van 't Hoff published his research on chemical kinetics, titled Études de Dynamique chimique ("Studies in Chemical Dynamics"), in which he described a new method for determining the order of a reaction using graphics, and applied the laws of thermodynamics to chemical equilibria. He also introduced the modern concept of chemical affinity. In 1886, he showed a similarity between the behaviour of dilute solutions and gases. He worked on Svante Arrhenius's theory of the dissociation of electrolytes and in 1889 provided physical justification for the Arrhenius equation. In 1896, Van 't Hoff became a lecturer in chemistry and physics at the Veterinary College in Utrecht. He then worked as a professor of chemistry, mineralogy, and geology at the University of Amsterdam for almost 18 years before eventually becoming the chairman of the chemistry department. In 1896 Van 't Hoff moved to Germany where he finished his career at the University of Berlin in 1911.

Hoff was a Dutch chemist who was awarded the first Nobel Prize in Chemistry in 1901 for his discovery of the laws of chemical dynamics and osmotic pressure in solutions. He also demonstrated that some isomers of carbon atoms structures could be explained if the four valence arranged themselves into a tetrahedron. His work on solutions showed dilute solutions follow the same mathematical properties describing gases.

Van't Hoff equation.

An equation for the variation with temperature T of the equilibrium constant K of a gaseous reaction in terms of the heat of reaction at constant pressure, Δ H: d (ln K)/ dT = Δ H/RT 2, where R is the gas constant. Also known as van't Hoff isochore.

Van’t hoff law: a statement in physical chemistry: the effect of a change in temperature on a system in equilibrium is to shift the equilibrium in the direction that acts to nullify the temperature change according to van't Hoff's law,an increase in temperature will cause an increase in the rate of an endothermic reaction.

Van’t hoff factor:is the relationship between the ideal value of a solution’s colligative properties and the observed colligative properties. The number of moles of particles in the solution in relation to the moles of solute dissolved will always be lower than the idea for ionic solutes.



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