Ameodeo Avogadro

 

AMEDEO AVOGADRO

Lorenzo Romano Amedeo Carlo Avogadro was born on 9^th August 1776 in Turin piedmont, Sardinia into a noble family in the kingdom of Sardinia (now part of Italy). His parents were distinguished Italian lawyers and his father, Filippo Avogadro, was a well-known magistrate and senator in the piedmont region of northern Italy. His mother, anna Vercellone of Biella, was a noblewoman.

Avogadro was a bright young man who did excellently in his studies. Being the child of lawyers, he decided to follow his father’s footsteps and studied law.

He graduated from jurisprudence in 1792, Avogadro continued with his doctorate study in law and four years later, when he was 20, he received his doctorate in ecclesiastical law.

After graduation, he began to practice his legal career and became the legal secretary to the prefecture of Eridano in 1801. Soon after Avogadro began to lose interest in legal matters.

He believed science was much more intellectually stimulating and began to develop an interest in physics and mathematics.

Referred to as positive philosophy then he began to study these subjects privately under the tutelage of the prominent mathematical physicist professor Vassalli Eandi.

Avogadro soon began to conduct his scientific researches with his focus on electricity.

In 1803, Avogadro worked together with his brother, Felice, to publish his first scientific paper, the paper focuses primarily on the electrical behavior of salt solutions.

In 1804, he quitted his legal practice after realizing that he was meant for a scientific career, he also became a corresponding member of the academy of sciences of Turin.

In 1806, Avogadro moved into academics and began to teach physics and mathematics at a high school in Vercelli, Turin.

1809, Avogadro became a professor of natural philosophy at the Royal College of Vercelli.

He maintained this post until 1820. One day, while Avogadro was experimenting with gas densities in Vercelli, he noticed something amazing, he combined two volumes of hydrogen gases with one volume of oxygen gas and two volumes of water vapor was produced.

Considering his understanding of gas densities at that time, he was expecting the combination to yield only a volume of water vapor and not two.

However, the experiment led him to conclude that the oxygen particles consisted of two atoms (he used the word molecules then).

Avogadro also described three different molecules types in his writing,

The integral molecules, which are very similar to our present-day molecules, constituent molecules, these form part of an element and elementary molecules, which are very similar to what we refer to as atoms now.

His study on elementary molecule was highly influential in the field of atomic theory.

Avogadro was not the only scientist in the field of molecules and gases. There were other two scientist- French chemist joseph Gay Lussac and English chemist John Dalton- who also explored these topics around the same time Avogadro was greatly influenced by the work of Gay-Lussac and Dalton.

Avogadro stated that he remembered Dalton for articulating the basics of atomic theory that “All Matter is composed of tiny indivisible particles called atoms.”

He remembered Gay-Lussac for his eponymous gas pressure-temperature law.

Avogadro began to make his major contribution to the scientific world in 1811, when he stated what was considered to be the biggest contribution to date – the molecular theory, now known as “Avogadro law”.

The law states that “Equal volumes of all gases at the same temperature and pressure contain the same number of molecules.”

Avogadro was also able to explicitly explain the Joseph-Louis and Gay-Lussacs law of combining volume of gases using his law.

That same year, he also discovered the correct molecular formula for hydrogen chloride, carbon monoxide, ammonia, nitrous oxide and water. He was credited to have established the existence of tetratomic elementary molecules. He was reportedly the first scientist to discover that elements can also exist in the form of molecules and not always as individual atoms.

He also proposed a constant, which was named after him “Avogadro constant”

Which is “The number of constituent particles usually atoms or molecules that are contained in the amount of substance given by one mole.”

The constant was experimentally determined to be 6.02214076×10²³ molecules per gram mole.

Avogadro received the first chair of mathematics and physics in 1820 at the university of Turin.

He furthered his scientific research and in 1821, he came up with the correct molecular formula for ether and alcohol.

In 1822, Avogadro lost his job at the University of Turin, the university was closed down due to civil disturbances. However, he was reappointed to the post in 1834 (some historical facts hold that Avogadro supported a group of people who were planning a revolution on the island of Sardinia, though the revolution was stopped by the concession of Charles Albert’s modern constitution, Avogadro was removed as a professor at the University of Turin due to his involvement in the political actions).

However, the increasing acceptance of his scientific work and revolutionary ideas led to his restatement at the university. Between 1843 and 1850, Avogadro wrote four papers on atomic volumes and using atomics volumes, Avogadro was able to assign affinity number for the elements.

The great scientist retired in 1850.

Avogadro scientific work did not receive much notice during this time though his works are now considered a foundational aspect of chemistry. Some historians believed that all Avogadro discoveries were overlooked because the scientist at the time worked in relative obscurity but Avogadro neither moved in their social circle nor corresponded with other major scientists, though he corresponded with other major scientists later in his career.

More so, Avogadro's scientific ideas were possibly neglected because they contradicted the standing ideas of those of more famous scientists, as a result only a few of his papers were translated into English and German during his lifetime.

It was Auguste Laurent and Charles Frederic Gerhardt who demonstrated through their studies on organic chemistry that Avogadro law explained why the same quantities of molecules in a gas have the same volume. However, other related experiments with some organic substances revealed some exceptions to Avogadro’s law, this further fuelled the rejection of the law.

Very little is known about Avogadro's private life, other than he was pragmatic, sober and a private man, who was quite religious. He was married at a much older-age 39 years though some claimed he was 42 years when he married. He got married to Felicita Mazze, the couple had six children -all sons. Avogadro died in 1856 at the age of 79, he died in Turin, piedmont-Sardinia.

Till his death Avogadro held a post that dealt with weights and measures, meteorology, and statistics. He reportedly introduced the metric system into piedmont. He was also a member of the Royal superior council of public instruction.

It was two years after Avogadro's death that his law generally accepted. This happened when Stanislao Cannizzaro an Italian chemist, was able to explain why there were some organic chemist exceptions to the Avogadro law as announced at Karlsruhe Congress in 1860. He explained that these organic chemical exceptions were because of molecular dissociations that took place within the chemical at a certain temperature. Stanislao Cannizzaro clarified some Avogadro ideas, which included his opinion on the relationship between atoms and molecules.

In 1857, Rodulf Clausius proposed his kinetic theory, with which he further provided evidence for Avogadro law.