Died: 2 February 1907, Saint Petersburg, Russia
Full name: Dmitri Ivanovich Mendeleev
Awards: Copley Medal, Demidov Prize
Children: Lyubov Dmitrievna Mendeleeva, Vasily Mendeleev, more
Education: Saint Petersburg State University (1855–1856), Saint Petersburg State University (1850–1855), Heidelberg University
Dmitri Ivanovich Mendeleev 8 February 1834 – 2 February 1907 was a Russian chemist and inventor. He formulated the Periodic Law, created a farsighted version of the periodic table of elements, and used it to correct the properties of some already discovered elements and also to predict the properties of eight elements yet to be discovered.
Mendeleev was born in the village of Verkhnie Aremzyani, near Tobolsk in Siberia, to Ivan Pavlovich Mendeleev and Maria Dmitrievna Mendeleeva (née Kornilieva). His grandfather was Pavel Maximovich Sokolov, a priest of the Russian Orthodox Church from the Tver region. Ivan, along with his brothers and sisters, obtained new family names while attending the theological seminary. Mendeleev was raised as an Orthodox Christian, his mother encouraging him to “patiently search divine and scientific truth.” His son would later inform that he departed from the Church and embraced a form of deism.
In 1863 there were 56 known elements with a new element being discovered at a rate of approximately one per year. Other scientists had previously identified periodicity of elements. John Newlands described a Law of Octaves, noting their periodicity according to relative atomic weight in 1864, publishing it in 1865. His proposal identified the potential for new elements such as germanium. The concept was criticized and his innovation was not recognized by the Society of Chemists until 1887. Another person to propose a periodic table was Lothar Meyer, who published a paper in 1864 describing 28 elements classified by their valence, but with no prediction of new elements.
After becoming a teacher in 1867, Mendeleev wrote the definitive textbook of his time: Principles of Chemistry (two volumes, 1868–1870). It was written as he was preparing a textbook for his course. This is when he made his most important discovery. As he attempted to classify the elements according to their chemical properties, he noticed patterns that led him to postulate his periodic table; he claimed to have envisioned the complete arrangement of the elements in a dream
“I saw in a dream a table where all elements fell into place as required. Awakening, I immediately wrote it down on a piece of paper, only in one place did a correction later seem necessary.
Unaware of the earlier work on periodic tables going on in the 1860s.
By adding additional elements following this pattern, Dmitri developed his extended version of the periodic table. On 6 March 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 atomic weight and valence. This presentation stated that
The elements, if arranged according to their atomic weight, exhibit an apparent periodicity of properties.
Elements which are similar regarding their chemical properties either have similar atomic weights (e.g., Pt, Ir, Os) or have their atomic weights increasing regularly (e.g., K, Rb, Cs).
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.
The elements which are the most widely diffused have small atomic weights.
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.
We must expect the discovery of many yet unknown elements–for example, two elements, analogous to aluminium and silicon, whose atomic weights would be between 65 and 75.
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. (Tellurium’s atomic mass is 127.6, and Mendeleev was incorrect in his assumption that atomic mass must increase with position within a period.)
Certain characteristic properties of elements can be foretold from their atomic weights.
Mendeleev published his periodic table of all known elements and predicted several new elements to complete the table. Only a few months after, Meyer published a virtually identical table. Some consider Meyer and Mendeleev the co-creators of the periodic table. Mendeleev has the distinction of accurately predicting of the qualities of what he called ekasilicon, ekaaluminium and ekaboron (germanium, gallium and scandium, respectively).
For his predicted eight elements, he used the prefixes of eka, dvi, and tri (Sanskrit one, two, three) in their naming. Mendeleev questioned some of the currently accepted atomic weights (they could be measured only with a relatively low accuracy at that time), pointing out that they did not correspond to those suggested by his Periodic Law. He noted that tellurium has a higher atomic weight than iodine, but he placed them in the right order, incorrectly predicting that the accepted atomic weights at the time were at fault. He was puzzled about where to put the known lanthanides, and predicted the existence of another row to the table which were the actinides which were some of the heaviest in atomic mass. Some people dismissed Mendeleev for predicting that there would be more elements, but he was proven to be correct when Ga (gallium) and Ge (germanium) were found in 1875 and 1886 respectively, fitting perfectly into the two missing spaces.
By giving Sanskrit names to his “missing” elements, Mendeleev showed his appreciation and debt to the Sanskrit grammarians of ancient India, who had created sophisticated theories of language based on their discovery of the two-dimensional patterns in basic sounds. Mendeleev was a friend and colleague of the Sanskritist Böhtlingk, who was preparing the second edition of his book on Pāṇini at about this time, and Mendeleev wished to honor Pāṇini with his nomenclature. Noting that there are striking similarities between the periodic table and the introductory Śiva Sūtras in Pāṇini’s grammar, Prof. Kiparsky says:
“The analogies between the two systems are striking. Just as Panini found that the phonological patterning of sounds in the language is a function of their articulatory properties, so Mendeleev found that the chemical properties of elements are a function of their atomic weights. Like Panini, Mendeleev arrived at his discovery through a search for the “grammar” of the elements… ”
The original draft made by Mendeleev would be found years later and published under the name Tentative System of Elements.
Dmitri Mendeleev is often referred to as the Father of the Periodic Table. He called his table or matrix, “the Periodic System”.
Draft by- Prajakta patankar