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Avogadro,
Amedeo, Count of Quaregna Italian physicist Born: Turin, Piedmont, June 9, 1776 Died: Turin, July 9, 1856 | |||||||||
Avogadro Becquerel Bohr Doppler Einstein Geiger Heisenberg Hertz Kirchhoff Planck Roentgen Rutherford Schrodinger |
Avogadro was appointed a professor of physics at the University of Turin, later in his life. He suffered the familiar fate of being neglected in his lifetime and only being recognized after his death. Avogadro experimented with gases and temperature, and decided that all gases (at a given temperature) must contain the same number of particles per unit volume. This was Avagadros hypothesis, which he advanced in a paper, published in 1811. He also noted that the particles might be either atoms or molecules. He observed that the electrolyzation of water produced twice as much hydrogen as oxygen, by volume. From this he was able to deduce that the oxygen atom was sixteen times as heavy as the hydrogen atom. The work of Avogadro was, however, rejected by Dalton, and ignored by Berzelius, the most prominent chemist of that time. The result is that there was ongoing confusion in differentiating atoms from molecules, and atomic weights from molecular weights. It was not until fifty years after its publication, that the hypothesis became accepted, mainly through the efforts of another Italian chemist, Cannizzaro. Today, the name of Avogadro is applied to the number of atoms, or molecules, present in a substance that has a mass of its atomic or molecular weight in grams. Thus 44 grams of carbon dioxide (molecular weight 44) contains a fixed number of molecules, and this number is known as Avogadros constant. The number is actually a rather large number, namely, 602,600 million trillion. | |||||||||
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