Amedeo Carlo Avogadro, conte di Quaregna e di Cerreto , was born in Turin, Italy, on 9th August, 1776. He was the son of Count Filippo Avogadro and Anna Maria Vercellone. Amedeo Avogadro went to school in Turin. Coming from a family of well established ecclesiastical lawyers, Avogadro was guided toward a legal career, and became a bachelor of jurisprudence in 1792, at the ripe old age of just 16 years. Four years later he gained his doctorate in ecclesiastical law and began to practice. In 1801 he was appointed secretary to the prefecture of the department of Eridano.
- Facts about Amedeo Avogadro 8: his important works The important works of Avogadro can be seen in the field of weight and measures, statistics and meteorology. He also created the Avogadro’s Law. His works mean a lot and they began to affect the thinking of other scientists.
- In 1811, Italian physicist and mathematician Amedeo Avogadro published a hypothesis (also termed Avogadro's law or principle) stating that the volume of a gas is directly proportional to the number of molecules of the gas. This is represented by the formula where a is a constant, V is the volume of the gas, and N is the number of gas molecules.
Amedeo Avogadro, in full Lorenzo Romano Amedeo Carlo Avogadro, conte di Quaregna e Cerreto, (born August 9, 1776, Turin, in the Kingdom of Sardinia and Piedmont Italy—died July 9, 1856, Turin), Italian mathematical physicist who showed in what became known as Avogadro’s law that, under controlled conditions of temperature and pressure, equal volumes of gases contain an equal number of molecules.
In spite of his successful legal career, Avogadro also showed an interest in natural philosophy, and in 1800 he began private studies of mathematics and physics. In 1806, Avogadro was appointed demonstrator at the Academy of Turin, and in 1809 became professor of natural philosophy at the college of Vercelli. In 1820, when the very first chair of mathematical physics in Italy was established at the University of Turin, Avogadro was appointed. Unfortunately, his post was short lived, since political changes suppressed the chair and Avogadro was out of a job by July, 1822. The chair was eventually reestablished in 1832, and Avogadro was reappointed to the position in 1834. Here he remained until his retirement in 1850.
Amedeo Avogadro Law Algebraic Expression
In order to understand the contribution that Avogadro made, we must consider some of the ideas being developed at this time. Chemistry was just beginning to become an exact science. The Law of Definite Proportions and the Law of Multiple Proportions were well accepted by 1808, at which time John Dalton published his New System of Chemical Philosophy.
Dalton proposed that the atoms of each element had a characteristic atomic weight, and that it was atoms that were the combining units in chemical reactions. Dalton had no method of measuring atomic weights unambiguously, so made the incorrect assumption that in the most common compound between two elements, there was one atom of each.
In 1811, Avogadro published an article in Journal de physique that clearly drew the distinction between the molecule and the atom. He pointed out that Dalton had confused the concepts of atoms and molecules. The 'atoms' of nitrogen and oxygen are in reality 'molecules' containing two atoms each. Thus two molecules of hydrogen can combine with one molecule of oxygen to produce two molecules of water. Avogadro suggested that equal volumes of all gases at the same temperature and pressure contain the same number of molecules, which became known as Avogadro's Principle.
The work of Avogadro was almost completely neglected until it was forcefully presented by Stanislao Cannizarro at the Karlsruhe Conference in 1860. He showed that Avogadro's Principle could be used to determine not only molar masses, but also, indirectly, atomic masses. The reason for the earlier neglect of Avogadro's work was probably the deeply rooted conviction that chemical combination occurred by virtue of an affinity between unlike elements. After the electrical discoveries of Galvani and Volta, this affinity was generally ascribed to the attraction between unlike charges. The idea that two identical atoms of hydrogen might combine into the compound molecular hydrogen was abhorrent to the chemical philosophy of the early nineteenth century.
As we all know today, Avogadro's number is very large, the presently accepted value being 6.0221367x1023. The size of such a number is extremely difficult to comprehend. Cannizarro, around 1860, used Avogadro's ideas to obtain a set of atomic weights, based upon oxygen having an atomic weight of 16. In 1865, Loschmidt used a combination of liquid density, gaseous viscosity, and the kinetic theory of gases, to establish roughly the size of molecules, and hence the number of molecules in 1 cm3 of gas.
During the latter part of the nineteenth century, it was possible to obtain reasonable estimates for Avogadro's number from sedimentation measurements of colloidal particles. Into the twentieth century, then Millikan oil drop experiment gave much better values, and was used for many years.
In 1811 Avogadro put forward a hypothesis that was neglected by his contemporaries for years. Eventually proven correct, this hypothesis became known as Avogadro’s law, a fundamental law of gases.
The contributions of the Italian chemist Amedeo Avogadro (1776–1856) relate to the work of two of his contemporaries, Joseph Louis Gay-Lussac and John Dalton. Gay-Lussac’s law of combining volumes (1808) stated that when two gases react, the volumes of the reactants and products—if gases—are in whole number ratios. This law tended to support Dalton’s atomic theory, but Dalton rejected Gay-Lussac’s work. Avogadro, however, saw it as the key to a better understanding of molecular constituency.
Avogadro’s Hypothesis
In 1811 Avogadro hypothesized that equal volumes of gases at the same temperature and pressure contain equal numbers of molecules. From this hypothesis it followed that relative molecular weights of any two gases are the same as the ratio of the densities of the two gases under the same conditions of temperature and pressure. Avogadro also astutely reasoned that simple gases were not formed of solitary atoms but were instead compound molecules of two or more atoms. (Avogadro did not actually use the word atom; at the time the words atom and molecule were used almost interchangeably. He talked about three kinds of “molecules,” including an “elementary molecule”—what we would call an atom.) Thus Avogadro was able to overcome the difficulty that Dalton and others had encountered when Gay-Lussac reported that above 100°C the volume of water vapor was twice the volume of the oxygen used to form it. According to Avogadro, the molecule of oxygen had split into two atoms in the course of forming water vapor.
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Edgar Fahs Smith Collection, Kislak Center for Special Collections, Rare Books and Manuscripts, University of Pennsylvania
Curiously, Avogadro’s hypothesis was neglected for half a century after it was first published. Many reasons for this neglect have been cited, including some theoretical problems, such as Jöns Jakob Berzelius’s “dualism,” which asserted that compounds are held together by the attraction of positive and negative electrical charges, making it inconceivable that a molecule composed of two electrically similar atoms—as in oxygen—could exist. In addition, Avogadro was not part of an active community of chemists: the Italy of his day was far from the centers of chemistry in France, Germany, England, and Sweden, where Berzelius was based.
Amedeo Avogadro Invention
Personal Life
Avogadro was a native of Turin, where his father, Count Filippo Avogadro, was a lawyer and government leader in the Piedmont (Italy was then still divided into independent countries). Avogadro succeeded to his father’s title, earned degrees in law, and began to practice as an ecclesiastical lawyer. After obtaining his formal degrees, he took private lessons in mathematics and sciences, including chemistry. For much of his career as a chemist he held the chair of physical chemistry at the University of Turin.
Amedeo Avogadro Atomic Theory
The information contained in this biography was last updated on November 30, 2017.