Scientist Dateline, November 27
Lars Onsager, Norwegian Chemist and Physicist
Credited for his discovery of the Onsager reciprocal relations, fundamental for the irreversible processes of thermodynamics.
Lars Onsager (November 27, 1903 – October 5, 1976) was a Norwegian-born American physical chemist and theoretical physicist, winner of the 1968 Nobel Prize in Chemistry. He held the Gibbs Professorship of Theoretical Chemistry at Yale University.
His research at Brown University was concerned mainly with the effects on diffusion of temperature gradients, and produced the Onsager reciprocal relations, a set of equations published in 1929. Two years later its form was expanded in statistical mechanics whose importance went unrecognized for many years. Their value became apparent during the decades following World War II. By 1968 they were considered important enough to gain him that year’s Nobel Prize in Chemistry. Continue reading
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Biochemist, Medical Doctor, and Nobel Laureate
Otto Heinrich Warburg (October 8, 1883 – August 1, 1970), a German physiologist, medical doctor and Nobel laureate, was the son of physicist Emil Warburg. One of the 20th century’s leading biochemists, his combined work in plant physiology, cell metabolism and oncology made him an integral figure in the later development of systems biology. He also worked with Dean Burk in photosynthesis to discover the I-quantum reaction that splits the carbon dioxide (CO2), activated by the respiration.
He won the Nobel Prize of 1931. An officer in the elite Ulan (cavalry regiment) during the First World War, he won the Iron Cross (1st Class) for bravery.
Otto Warburg’s father, Emil Warburg, was a member of the illustrious Warburg family of Altona. Continue reading
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Chemist, Physicist and Meteorologist, famous for Atomic Theory
An English chemist, meteorologist and physicist, John Dalton (1766-1844), is most famous today for his modern concept of atoms best known as Dalton’s Atomic Theory, the concept that defines science in terms of the atomic theory of elements. He is also famous for the “Dalton’s Law of Multiple Proportions” and “Dalton’s Law of Partial Pressures.”
Through patience, commitment and dedication to work, Dalton developed a concept that material is made of many different types of atoms. This was a vital and critical insight, one that gave birth to the science of chemistry. A bachelor and devout Quaker, Dalton studied patiently the properties of gases and began to provide a framework that enabled scientists to make sense of chemical reactions, and therefore, making accurate predictions of outcomes in mixing different types of atoms.
John Dalton’s Early Years
John Dalton was born on 6 September 1766 in the Cockermouth English Lake District to a Quaker tradesman family. Continue reading
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Profiles of women scientists who made significant contributions to 20th-century’s science development
1. Hazel Bishop (1906-1998)
She was an American chemist and cosmetics manufacturer, born in New Jersey, who founded her own company Hazel Bishop, Inc. In 1950 she invented “lasting lipstick”, the first of the “non-smear, long lasting” type. Her sales rose to millions in the early 1950s. She continued to experiment, creating other beauty products. Bishop became the head of the cosmetics marketing program at the Fashion Institute of Technology in 1978. She was the first person to occupy the Revlon Chair at Fashion Institute of Technology.
2. Annie Jump Cannon (1863-1941)
She was an American astronomer from Dover, Delaware. She was educated at Wellesley and Radcliffe and joined the Harvard College Observatory in 1911 as curator of astronomical photographers. In 1938, she was appointed William Cranch Bord Astronomer at Harvard where she spent her entire career. Cannon classified some 400,000 stars in her lifetime and published The Henry Draper Catalogue which classified the spectra of all stars from the North to the South Poles as studied by photographing their light through a refracting prism.
3. Marie Curie (1867-1934)
A polish-born French chemist and physicist, Marie Curie is famous for radioactivity. She discovered polonium and radium and the first woman to win two Nobel prizes, one for physics in 1903, and another in 1911 for chemistry. Continue reading
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When a chemical element is heated to incandescence, it produces its own characteristic lines in the spectrum of light.
As chemistry students many of us will never forget the Bunsen burner as a constant laboratory companion in our numerous “flame test” experiments. Bunsen developed the burner in 1855. The test is used to identify the presence of a particular metal by the colour of the flames produced. The burner’s non-luminous flame is basically used as it does not interfere with the coloured flame given off by the sample metal being tested.
Bunsen-Kirchhoff Spectroscopy theory and other Discoveries
Together, Bunsen and Kirchhoff developed the first spectroscope, a device used to produce and observe a spectrum. Using their spectroscope, in 1860, they went on to discover two elements: caesium and rubidium. These discoveries ushered a new era in the means used to find new chemical elements. The first 50 elements discovered (beyond those known since ancient times) were either the products of chemical reactions or were released by electrolysis. From 1860, however, thanks to Burner and Kirchhoff, the search was on for trace elements detectable only with the help of specialized instruments like the spectroscope. The Bunsen–Kirchhoff Award for spectroscopy is named after Bunsen and Kirchhoff.
Kirchhoff also discovered that when heated to incandescence, each chemical element produced its own characteristic lines in the spectrum. For instance, sodium (Na) has a spectrum with two yellow lines, wavelengths about 588 and 589 nanometres. Extending experiments beyond Bunsen and Kirchhoff, later scientists were able to determine the presence of elements, for example, in the sun or stars once similar wavelengths were identified in their spectra. Continue reading