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BIOGRAPHIES OF GREAT SCIENTISTS
Avogadro Amedeo. Biography of a scientist
Directory / Biographies of great scientists
Avogadro entered the history of physics as the author of one of the most important laws of molecular physics. Lorenzo Romano Amedeo Carlo Avogadro di Quaregna e di Cerreto was born on August 9, 1776 in Turin, the capital of the Italian province of Piedmont, in the family of Filippo Avogadro, an employee of the judicial department. Amedeo was the third of eight children. His ancestors from the XII century were in the service of the Catholic Church as lawyers and, according to the tradition of that time, their professions and positions were inherited. When the time came to choose a profession, Amedeo also took up law. In this science, he quickly succeeded and at the age of twenty he received the degree of Doctor of Church Law. Legal practice did not fascinate Amedeo, his interests were far from jurisprudence. In his youth, he briefly attended the so-called school of geometry and experimental physics. It was she who awakened in him a love for these sciences. But, not having received enough systematic knowledge, he was forced to engage in self-education. When he was already 25 years old, he began to devote all his free time to the study of physical and mathematical sciences. Avogadro began his scientific career with the study of electrical phenomena. This interest intensified especially after Volta invented the first source of electric current in 1800, and also in connection with the discussion between Galvani and Volta about the nature of electricity. These questions were at the forefront of science at that time, and it is natural that the young Avogadro decided to try his hand here. Avogadro's works, devoted to various problems of electricity, appeared until 1846. He also paid great attention to research in the field of electrochemistry, trying to find a connection between electrical and chemical phenomena, which led him to create a kind of electrochemical theory. In this respect, his research was in contact with the work of the famous chemists Davy and Berzelius. In 1803 and 1804, Amedeo, together with his brother Felice, presented two papers on the theory of electrical and electrochemical phenomena to the Turin Academy of Sciences, for which he was elected in 1804 a corresponding member of this academy. In his first work, entitled Analytical Note on Electricity, he explained the behavior of conductors and dielectrics in an electric field, in particular the phenomenon of polarization of dielectrics. The ideas expressed by him were then more fully developed in the works of other scientists, in particular Ampère. In 1806, Avogadro got a job as a tutor at the Turin Lyceum, and then, in 1809, he was transferred as a teacher of physics and mathematics to the Vercelli Lyceum, where he worked for about ten years. During this period, he gets acquainted with a huge amount of scientific literature, making numerous extracts from the books and journal articles he read. These extracts, which he did not stop keeping until the end of his days, amounted to 75 volumes of approximately 700 pages each! The content of these volumes testifies to the versatility of Avogadro's interests, to the colossal work that he did, "retraining" from a lawyer to a physicist. Avogadro arranged his family life quite late, when he was already over thirty. While working in Vercelli, he met his future wife Anna Maria Mazzie di Giuseppe, the daughter of a notary who was 18 years younger than him. From this marriage he had eight children - two sons and six daughters. None of them inherited his profession and interests. In 1808, the French scientist Gay-Lussac, studying reactions between gases, found that the volumes of reacting gases and gaseous reaction products are related as small integers. And in 1811, Avogadro's article "Essay on the method for determining the relative masses of the elementary molecules of bodies and the proportions according to which they are included in compounds" appears. Outlining the basic ideas of the molecular theory, Avogadro showed that it not only does not contradict the data obtained by Gay-Lussac, but, on the contrary, is in excellent agreement with them and opens up the possibility of accurately determining the atomic masses, the composition of molecules and the nature of the chemical reactions taking place. To do this, first of all, it is necessary to imagine that the molecules of hydrogen, oxygen, chlorine and some other simple substances do not consist of one, but of two atoms. In the same work, Avogadro came to the following important conclusion: "... the number ... of molecules is always the same in the same volumes of any gases." Of course, if the volumes are measured at the same pressures and temperatures. He further wrote that "there is now a very easy means of determining the relative masses of the molecules of bodies which can be obtained in the gaseous state, and the relative number of molecules in compounds." Thanks to the new law, Avogadro was the first to obtain, in particular, the correct formula for the reaction of water formation. In 1814, Avogadro's second article appeared, "Essay on the relative masses of the molecules of simple bodies, or the supposed densities of their gas, and on the constitution of some of their compounds." Avogadro's law is clearly formulated here: "... equal volumes of gaseous substances at the same pressures and temperatures correspond to an equal number of molecules, so that the densities of various gases are a measure of the masses of the molecules of the corresponding gases." Further in the article, the applications of this law to determine the composition of the molecules of numerous inorganic substances are considered. Since the mass of one mole of a substance is proportional to the mass of a single molecule, Avogadro's law can be formulated as the statement that a mole of any substance in the gaseous state at the same temperatures and pressures occupies the same volume. As experiments have shown, under normal conditions, the number of molecules in a mole of any substance is the same. It is called Avogadro's number. This number is one of the most important universal constants of modern physics and chemistry. It is used in determining a number of other universal constants, for example, the Boltzmann constant, the Faraday constant, etc. The Avogadro number can be determined by many independent methods. The excellent agreement of the values obtained in this case was a convincing proof of the reality of molecules and the validity of the molecular-kinetic theory. In 1821, in the article "New considerations on the theory of certain proportions in compounds and on the determination of the masses of the molecules of bodies," Avogadro summed up his almost ten years of work in the field of molecular theory and extended his method for determining the composition of molecules to a number of organic substances. In the same article, he showed that other chemists, primarily Dalton, Davy and Berzelius, who were unfamiliar with his work, continue to hold incorrect views on the nature of many chemical compounds and the nature of the reactions occurring between them. In September 1819, Avogadro was elected a member of the Turin Academy of Sciences. By this time, he had already gained fame among his colleagues for his work in the field of molecular theory, electricity and chemistry. In 1820, by royal decree, Avogadro was appointed the first professor of the new department of higher physics at the University of Turin. Interesting are the views of Avogadro on the teaching of physics, expressed by him when he took this position. Italian science at that time was still very poorly developed. In an effort to help his homeland catch up in the level of development of the natural sciences with other European countries, Avogadro outlined an extensive plan of action. His main idea was the need to combine teaching with scientific activity. These progressive ideas were not destined to come true because of the military and political events in Italy in the early twenties. In 1822, after student unrest, the Turin University was closed for a year by the authorities, and a number of its new departments, including the Department of Higher Physics, were liquidated. Nevertheless, in 1823, Avogadro received the honorary title of honored professor of higher physics and was appointed senior inspector of the House for the Control of Public Expenditures - a financial and legal position, very far from science. Despite the new responsibilities, Avogadro continued to engage in scientific research. In 1833, the University of Turin again received the chair of higher physics, but it was offered not by Avogadro, but by the famous French mathematician Augustin Louis Cauchy, who left his homeland in 1830. Only two years later, after Cauchy's departure, Avogadro was able to take this chair, where he worked until 1850. In the same year he left the university, passing the chair to his student Felice Cue. In the years 1837-1841, Avogadro published a four-volume work "Physics of weighty bodies, or a treatise on the general constitution of bodies." Each volume had over 900 pages. By this time, Avogadro was already 65 years old, but his mind was still clear, and his love for science and industriousness were inexhaustible. This work turned out to be the first ever textbook on molecular physics. Contemporaries in their memoirs draw Avogadro as a very modest, impressionable and charming person. They note his goodwill, sincerity in dealing with other people. "Highly educated without pedantry, wise without swagger, despising luxury, not caring about wealth, not striving for honors, indifferent to his own merits and his own fame, modest, moderate, benevolent" - this is how one of his contemporaries characterizes Avogadro. In his indifference to honors, he was a rare exception among the scientists of his time. After leaving the university, Avogadro served for some time as a senior inspector of the Control Chamber, and was also a member of the Higher Statistical Commission, the Higher Council of Public Education and the chairman of the Commission for Weights and Measures. Despite his venerable age, he continued to publish his research in the proceedings of the Turin Academy of Sciences. His last work was published three years before his death, when Avogadro was 77 years old. He died in Turin on 9 July 1856 and is buried in the family vault at Vercelli. The year after Avogadro's death, in recognition of his services to science, a bronze bust of him was erected at the University of Turin. Avogadro's enormous contribution to the development of molecular theory for a long time remained practically unnoticed by his contemporaries. And even much later, this law was often called the Avogadro-Ampère law in the literature, although Avogadro formulated it three years earlier than Ampère. Up until the early 1858s, arbitrariness reigned in chemistry, both in the estimation of molecular weights and in the description of chemical reactions; there were many misconceptions about the atomic composition of many complex substances. It even went as far as attempts to abandon molecular concepts altogether. Only in XNUMX, the Italian chemist Cannizzaro, having read Ampère's letter to Bertholla, in which there is a reference to the works of Avogadro, "rediscovered" these works and was surprised to see that they bring complete clarity to the confused picture of the state of chemistry of that time. In 1860, Cannizzaro spoke in detail about the work of Avogadro at the First International Chemical Congress in Karlsruhe, and his report made a huge impression on the scientists present there. As one of them said, he felt the veil fall from his eyes, the doubts disappeared, and instead there was a calm sense of certainty. The great Russian chemist Mendeleev, who also participated in the work of this congress, wrote later: “In the 50s, some took the atomic weight of oxygen equal to 8, others - 16. Trouble, inconsistency prevailed. In 1860, chemists from all over the world gathered in Karlsruhe in order to in order to reach an agreement, uniformity. Having been present at this congress, I vividly remember how great the disagreement was and how then the followers of Gerard ardently pursued the consequences of the law of Avogadro. Truth, in the form of the law of Avogadro-Gerard, through the congress, became more widely disseminated and soon after conquered all minds. Then the new atomic weights strengthened by themselves, and already from the 70s they came into general use. " Avogadro's merits as one of the founders of molecular theory have since received universal recognition. Author: Samin D.K.
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