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Amedeo Avogadro Biography

History of Avogadro

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Portrait of Avogadro

Portrait of Avogadro

Amedeo Avogadro was born August 9, 1776 and died July 9, 1856. He was born and died in Turin, Italy. Amedeo Avodagro, conte di Quaregna e Ceretto, was born into a family of distinguished lawyers (Piedmont Family). Following in his family's footsteps, he graduated in ecclesiastical law (age 20) and began to practice law. However, Avogadro also was interested in the natural sciences and in 1800 he began private studies in physics and mathematics. In 1809, he started teaching the natural sciences in a liceo (high school) in Vericelli. It was in Vericelli that Avogadro wrote a memoria (concise note) in which he declared the hypothesis that is now known as Avogadro's law. Avogadro sent this memoria to De Lamétherie's Journal de Physique, de Chemie et d'Histoire naturelle and it was published in the July 14th edition of this journal under the title Essai d'une manière de déterminer les masses relatives des molecules élémentaires des corps, et les proportions selon lesquelles elles entrent dans ces combinaisons. In 1814 he published a memoria about gas densities, Mémoire sur les masses relatives des molécules des corps simples, ou densités présumées de leur gaz, et sur la constitution de quelques-uns de leur composés, pour servir de suite à l'Essai sur le même sujet, publié dans le Journal de Physique, juillet 1811. In 1820, Avogadro became the first chair of mathematical physics at Turin University. In 1821, he published Nouvelles considérations sur la théorie des proportions déterminées dans les combinaisons, et sur la détermination des masses des molécules des corps and also Mémoire sur la manière de ramener les composès organiques aux lois ordinaires des proportions déterminées. In 1841, Avogadro completed and published his 4-volume work, Fisica dei corpi ponderabili, ossia Trattato della costituzione materiale de' corpi.

Not much is known about Avogadro's private life. He had six children and was reputed to be a religious man and also a discreet lady's man. Some historical accounts indicate that Avogadro sponsored and aided Sardinians planning a revolution on that island, stopped by the concession of Charles Albert's modern Constitution (Statuto Albertino). Because of his alleged political actions, Avogadro was removed as professor at Turin University (officially, the University was "very glad to allow this interesting scientist to take a rest from heavy teaching duties, in order to be able to give a better attention to his researches"). However, doubts remain as to the nature of Avogadro's association with the Sardinians. In any case, increasing acceptance of both revolutionary ideas and Avogadro's work led to his reinstatement at Turin University in 1833. Avogadro introduced the decimal system in Piedmont and served as a member of the Royal Superior Council on Public Instruction.

Avogadro's Law

Avogadro's law states that equal volumes of gases, at the same temperature and pressure, contain the same number of molecules. Avogadro's hypothesis wasn't generally accepted until after 1858 (after Avogadro's death), when the Italian chemist Stanislao Cannizzaro was able to explain why there were some organic chemical exceptions to Avogadro's hypothesis. One of the most important contributions of Avogadro's work was his resolution of the confusion surrounding atoms and molecules (although he didn't use the term 'atom'). Avogadro believed that particles could be composed of molecules and that molecules could be composed of still simpler units, atoms.The number of molecules in a mole (one gram molecular weight) was termed Avogadro's number (sometimes called Avogadro's constant) in honor of Avogadro's theories. Avogadro's number has been experimentally determined to be 6.023x1023 molecules per gram-mole.

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