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1950 - Arthur Jeffrey Dempster died. Dempster was a Canadian-American physicist who designed and built the first mass spectrometer. Mass spectrometers are used to separate a sample's components by mass. He later used this device to discover the uranium isotope U-235, the main isotope used in atomic bombs. 1920 - Nicolaas Bloembergen was born. Bloembergen is a Dutch-American physicist who shares half the 1981 Nobel Prize in Physics with Arthur Schawlow for the development of laser spectroscopy. Kai Siegbahn's research into the development of electron spectroscopy earned him the other half of the prize. 1892 - Archibald Scott Couper died. James Irvine/Journal of Chemical Education (1930)Couper was a Scottish chemist who described the methods carbon atoms could bond together to form large molecules. He was also the first to describe molecules by element symbols connected by dashes to represent the bonds between the atoms. 1818 - Henri-Étienne Sainte-Claire Deville was...

March 11th marks the passing of Archibald Scott Couper. Couper was a Scottish chemist who discovered carbon atoms were tetravalent and could form long chain molecules. Prior to this discovery, molecules were believed to possess one central atom, but the structures of many organic compounds could not be explained by this theory. Couper passed his paper to Charles Adolphe Wurtz to present at the French Academy of Sciences. Unfortunately, Wurtz procrastinated on passing the paper to the Academy and Couper lost priority to German chemist, August Kerkule who also discovered carbon could form bonds and determined the ring structure of benzene. Couper did not take the loss well and never published a scientific paper for the rest of his life. One lasting contribution Couper gave to chemistry was the way chemical structures are drawn. He was the the first to draw structures where element symbols were connected by lines that represent the bonds between them. Find out what else occurred on th...