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.

CHILDHOOD & EARLY LIFE

>> Lorenzo Romano Amedeo Carlo Avogadro di Quaregna e di Cerreto was born on 9 August 1776, in Turin, Piedmont-Sardinia into a noble family. His father was Filippo Avogadro, conte di Quaregna e Cerreto, a distinguished lawyer and senator in the Piedmont region of northern Italy.

>> He was a bright young man who excelled in his studies. He followed in his father’s footsteps and studied law, graduating in jurisprudence in 1792. He proceeded to receive his doctorate in ecclesiastical law four years later.

CAREER

>> He ventured into a legal career and became secretary to the prefecture of Eridano in 1801. Around this time he grew increasingly interested in physics and mathematics and began studying these subjects privately with the guidance of the prominent mathematical physicist Professor Vassalli Eandi.

>> Soon he also began his scientific researches, focusing primarily on electricity. He collaborated with his brother Felice to publish his first scientific paper in 1803. This paper examined the electrical behavior of salt solutions.

>> In 1804, he became a corresponding member of the Academy of Sciences of Turin. By this time he had realized that he was meant for a scientific career and left his legal practice.

>> He embarked into academics and started teaching mathematics and physics at a high school in Turin in 1806. He became a professor of natural philosophy at the Royal College of Vercelli in 1809, a post he held until 1820.

>> It was in 1811 that he first stated what would become his biggest contribution to science: the hypothesis that equal volumes of all gases at the same temperature and pressure contain the same number of molecules. He also explained the French chemist Joseph-Louis Gay-Lussac’s law of combining volumes of gases using this hypothesis.

>> He is credited to have recognized the existence of monatomic, triatomic, and tetratomic elementary molecules. In 1811, he also provided the correct molecular formula for water, nitric and nitrous oxides, ammonia, carbon monoxide, and hydrogen chloride.

>> In 1820, he accepted the first chair of mathematical physics at the University of Turin. Furthering his research, he came up with the correct formula for alcohol and ether in 1821.

>> Due to civil disturbances, the university was closed down and Avagadro lost his job in 1822. Avogadro was reappointed to the post a few years later in 1834.

>> Between 1843 and 1850, he authored four memoirs on atomic volumes and designated affinity numbers for the elements using atomic volumes. He retired in 1850.

MAJOR WORKS

>> He hypothesized what later became known as the Avogadro’s law. It is an experimental gas law relating volume of a gas to the amount of substance of gas present. The law states that, “equal volumes of all gases, at the same temperature and pressure, have the same number of molecules.”

>> In 1811, Avogadro proposed that the volume of a gas (at a given pressure and temperature) is proportional to the number of atoms or molecules regardless of the nature of the gas. The Avogadro constant named after him, is the number of constituent particles, usually atoms or molecules that are contained in the amount of substance given by one mole.

PERSONAL LIFE & LEGACY

>> He married quite late in life. He tied the knot with Felicita Mazzé in 1815. The couple had six children.

>> He died on 9 July 1856, at the age of 79.

>> A hardworking and modest person, he did not receive much acclaim for his works during his lifetime though his contributions to science were recognized years after his death.