1800-1875(wolfe.defoe)

== John Dalton was born in Cumberland on September 6, 1766 and died on July 27, 1844.He was born into a Quaker family and followed the beliefs of the religious movement his whole life.Dalton was almost completely colorblind himself and dedicated much research to the subject in the late 1700s, publishing the first paper on the subject in 1798.In his honor, colorblindness is sometimes referred to as Daltonism.Besides his Atomic Theory, for which he is most famous, Daltonis credited with writing the law of partial pressures of gasses, which means that gasses function independently of each other and exert differing pressures on the surrounding atmosphere, and the Law of Multiple Proportions, which stated that gasses will always combine in whole number ratios. == == John Dalton’s most important work is considered to be his Atomic Theory, which consists of 4 statements that list the characteristics that Dalton believed most accurately describe atoms.His Theory states that all elements are made up of tiny particles called atoms which cannot be destroyed, that every atom in an element is identical, that elements combine to form chemical compounds, and that chemical reactions result in the reorganization of atoms. Every part of this theory has been proved to be true excepting the indestructibility of atoms, which may occur during nuclear fission.These ideas can be traced all the way back to Democritus, who also believed that everything was composed of atoms and that they were indestructible. ==

Amedeo Avogadro was born on August 9, 1776 in Turin, Italy and died in the same city on July 9, 1856.He taught physical chemistry at the University of Turin for over 20 years, and as can be expected, this time allowed him to develop an extraordinarily deep knowledge of the science of chemistry.There are rumors that he helped various rebellions on an Italian island, and he allegedly lost his position at Turin for this support, though the head of the school claimed that it was to give him time to focus on his research, unburdened by his teaching load.Avogadro is one of the first to state that particles are composed of molecules, which are in turn composed of what he called simple molecules, which we call atoms.The number 6.02x1023, which is used to determine the number of something in one mole of that substance, is named after him for his contributions to chemistry.

His most important contribution to chemistry is known as Avogadro’s Law, which states that all gases that are at the same volume, temperature, and pressure contain the same number of molecules.This law allows chemists to calculate the molecular weight of gases, and if the molecular formula is known, the weight of each atom in the gas.Though it was not well received at the time of publication, it was verified by various other scientists after his death.Any chemist will agree that Avogadro’s Law was a massive step forward in the evolution of chemistry.

[|http://www.britannica.com/EBchecked/topic/45884/Amedeo-Avogadro#] []

Dmitri Mendeleev is one of the most important figures in Russian scientific history, a position that he attained by rising from the bottom of the social scale and putting in years of hard work.He was born in Siberia on February 8, 1834 as the youngest of 14 siblings.At the age of 13, his father died and his mother’s glass factory burned down, which necessitated relocating from Siberia.At first, the family went to Moscow, but the tense political atmosphere made it impossible for Mendeleev to apply to the University of Moscow because he was not from the city, so the family moved on to St. Petersburg, where Mendeleev would apply, get accepted, and eventually become a professor and the head of the chemistry department, transforming the city into a global mecca for chemical research.Mendeleev is one of the founders of the Russian Chemical Society and is credited with introducing the metric system to Russia.One of his finest moments occurred when he was the Director of the Bureau of Weights and Measures.While in this position, he created new standards that required vodka to be at least 40% alcohol by volume, which became a law!Mendeleev died in St. Petersburg on February 2, 1907.

The highlight of Mendeleev’s career as a chemist was his creation of the first periodic table of the elements, which is the method used to organize and classify elements by their atomic masses and chemical characteristics.The periodic table is separated into periods, or rows, and families, or columns.Elements are arranged in according to their atomic number from low to high.He was studying the various known elements at the time and attempting to classify them by their different traits and noticed repeating trends, which led him to design the first periodic table.Mendeleev said that atoms with the smallest mass are the most prevalent, that some traits of elements can be predicted by their atomic masses, and that there are many more elements to be discovered before the periodic table can be complete.

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Mendeleev's Original Periodic Table



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