Amedeo Avogadro Biography

The Scientist Who Penned Avogadro’s Law

Engraved portrait of Amedeo Avogadro
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Amedeo Avogadro was born August 9, 1776, and died July 9, 1856. He was born in and died in Turin, Italy.

Early Life and Education

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 was also interested in the natural sciences, and in 1800, he began private studies in physics and mathematics.

Career and Personal Life

In 1809, Avogadro started teaching the natural sciences in a liceo (high school) in Vericelli. It was in Vericelli that he 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. In 1814, he published a memoria about gas densities, In 1820, Avogadro became the first chair of mathematical physics at Turin University.

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 a 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 research"). 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 gasses, 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.