Amedeo Avogadro was an Italian scientist who formulated what is now known as Avogadro's law. Hailed as a founder of the atomic-molecular theory, he was the first scientist to realize that elements could exist in the form of molecules rather than as individual atoms. His biggest contribution to science, the Avogadro's law states that equal volumes of gases under the same conditions of temperature and pressure will contain equal numbers of molecules. Born into a noble family as the son of a distinguished lawyer, he followed in his father’s footsteps as a young man and graduated in ecclesiastical law. However, his interest in law waned once he developed a keen interest in what was then known as positive philosophy: physics and mathematics. Deciding to dedicate his life to science, he began studying mathematics and physics privately and soon embarked into research as well. Leaving behind his legal career, he became an educator and remained so for the rest of his life. A prolific researcher, he performed extensive studies on how the basic particles of matter behaved and postulated a hypothesis stating that equal volumes of all gases at the same temperature and pressure contain the same number of molecules. However, his great contribution to chemistry was recognized only after his death.