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Dmitri Mendeleev

Dmitri Medeleev Dmitri Mendeleev (8 February 1834 – 2 February 1907), was a Russian chemist and inventor. He is credited as being the creator of the first version of the periodic table of elements. Unlike other contributors to the table, Mendeleev predicted the properties of elements yet to be discovered.

Dmitri Mendeleev was born in Tobolsk, Siberia, Russia on February 8, 1834. Mendeleev was the youngest child of 17 siblings. At the age of 13, after the passing of his father and the destruction of his mother's factory by fire, Mendeleev attended the Gymnasium in Tobolsk.

In 1849, the now poor Mendeleev family relocated to St. Petersburg, where he entered the Main Pedagogical Institute in 1850. After Dmitri graduated, an illness that was diagnosed as tuberculosis caused him to move to the Crimean Peninsula on the northern coast of the Black Sea in 1855. While there he became chief science master of the Simferopol gymnasium №1. He returned with fully restored health to St. Petersburg in 1857.

Between 1859 and 1861, Mendeleev worked on the capillarity of liquids and the workings of the spectroscope in Heidelberg. In late August of 1861 Dmitri wrote his first book on the spectroscope in which it received high acclaim. In 1862, he married Feozva Nikitichna Leshcheva. Mendeleev became Professor of Chemistry at the Saint Petersburg Technological Institute and the University of St. Petersburg in 1863 he achieved tenure in 1867, and by 1871 had transformed St. Petersburg into an internationally recognized center for chemistry research. In 1865 he became Doctor of Science for his dissertation "On the Combinations of Water with Alcohol".

An older Dmitri Mendeleev After becoming a teacher, he wrote the definitive two-volume textbook at that time: Principles of Chemistry (1868-1870). As he attempted to classify the elements according to their chemical properties, he noticed patterns that led him to create his Periodic Table.

Unknown to Mendeleev, several other scientists had also been working on their own tables of elements. One was John Newlands, who published his Law of Octaves in 1865. However, the lack of spaces for undiscovered elements and the placing of two elements in one box were criticized and his ideas were not accepted.

On March 6, 1869, Mendeleev made a formal presentation to the Russian Chemical Society, entitled The Dependence between the Properties of the Atomic Weights of the Elements, which described elements according to both weight and valence. This presentation stated that:

1. The elements, if arranged according to their atomic mass, exhibit an apparent periodicity of properties.
2. Elements which are similar as regards to their chemical properties have atomic weights which are either of nearly the same value (e.g., Pt, Ir, Os) or which increase regularly (e.g., K, Rb, Cs).
3. The arrangement of the elements in groups of elements in the order of their atomic weights corresponds to their so-called valencies, as well as, to some extent, to their distinctive chemical properties; as is apparent among other series in that of Li, Be, B, C, N, O, and F.
4. The elements which are the most widely diffused have small atomic weights.
5. The magnitude of the atomic weight determines the character of the element, just as the magnitude of the molecule determines the character of a compound body.
6. We must expect the discovery of many yet unknown elements–for example, two elements, analogous to aluminum and silicon, whose atomic weights would be between 65 and 75.
7. The atomic weight of an element may sometimes be amended by a knowledge of those of its contiguous elements. Thus the atomic weight of tellurium must lie between 123 and 126, and cannot be 128. Here Mendeleev was wrong as the atomic mass of tellurium (127.6) remains higher than that of iodine (126.9).
8. Certain characteristic properties of elements can be foretold from their atomic weights.

Only a few months after Mendeleev published his periodic table of all known elements (and predicted several new elements to complete the table). As others before him had done, he questioned the accuracy of accepted atomic weights, pointing out that they did not correspond to those predicted by the Periodic Law. He noted that tellurium has a higher atomic weight than iodine, but he placed them in the correct order, assuming that the accepted atomic weights at the time were incorrect. He was puzzled about where to put the known lanthanides, and predicted the existence of another row to the table, the actinides, which were some of the heaviest in atomic mass.

mendeleev-table-5th.jpg Initially, Mendeleev was derided for there being gaps in the table. Ultimately though, he was vindicated when previously unknown elements (notably scandium, gallium and germanium) were discovered that filled in these holes and possessed properties (atomic weight, density, melting point, etc.) close to what Mendeleev predicted.

In 1876, he became obsessed with Anna Ivanova Popova and began courting her; in 1881 he proposed to her and threatened suicide if she refused. His divorce from Leshcheva was finalized one month after he had married Popova in early 1882. Even after the divorce, Mendeleev was technically a bigamist; the Russian Orthodox Church required at least 7 years before lawful re-marriage. His divorce and the surrounding controversy contributed to his failure to be admitted to the Russian Academy of Sciences (despite his international fame by that time). His daughter from his second marriage, Lyubov, became the wife of the famous Russian poet Alexander Blok. His other children were son Vladimir (a sailor, he took part in the notable Eastern journey of Nicholas II) and daughter Olga, from his first marriage to Feozva, son Ivan and a pair of twins from Anna.

Though Mendeleev was widely honored by scientific organizations all over Europe, including the Copley Medal from the Royal Society of London, he resigned from St. Petersburg University on August 17, 1890.

In 1893, Dmitri was appointed to be Director of the Bureau of Weights and Measures. It was in this role that he was directed to formulate new state standards for the production of vodka. His fascination with molecular weights led him to conclude that to be in perfect molecular balance, vodka should be produced in the ratio of one molecule of ethyl alcohol diluted with five molecules of water, giving a dilution by volume of approximately 38% alcohol to 62% water. As a result of his work, in 1894 new standards for vodka were introduced into Russian law and all vodka had to be produced at 40% alcohol by volume.

Mendeleev also investigated the composition of oil fields, and helped to found the first oil refinery in Russia.

Mendeleev died in 1907 in St. Petersburg, Russia from influenza. The Mendeleev crater on the Moon, as well as element number 101, the radioactive mendelevium, are named after him.

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