Italian chemist and mathematician born in Turin (1776-1856). Avogadro was schooled to be an ecclesiastical lawyer, but retained an interest in natural philosophy, and studied mathematics and physics on his own. In 1811, Avogadro made the first distinction between molecules and atoms. He further suggested Avogadro’s Law: Equal volumes of gas at the same pressure and temperature contain the same number of molecules. Avogadro's number, which defines the number of atoms in a mole, is named after him for his disambiguation of molecules.