Amedeo Avogadro conte di Quaregna

Avogadro, Amedeo, Conte di Quaregna (1776–1856) Italian physicist and chemist. His hypothesis, Avogadro's law (1811), states that equal volumes of gases at the same pressure and temperature contain an equal number of molecules. This led later physicists to determine that the number of molecules in one gram molecule (the relative molecular mass expressed in grams) is constant for all gases. This number, called Avogadro's number, equals 6.02257 × 10²³. It is both the ratio of the universal gas constant to Boltzmann's constant and of Faraday's constant to the charge of the electron.

Amedeo Avogadro, conte di Quaregna , 1776-1856, Italian physicist, b. Turin. He became professor of physics at the Univ. of Turin in 1820. In 1811 he advanced the hypothesis, since known as Avogadro's law, that equal volumes of gases under identical conditions of pressure and temperature contain the same number of molecules. Since then, through the work of other physicists, the number of molecules in the gram molecular volume has been determined and found to be the same for all gases. This number (6.02×10 ²³ ) has been called Avogadro's number . Avogadro's hypothesis, though not accepted for some fifty years after its introduction, is now one of the fundamental concepts of the atomic theory of matter.