Today (February 2, 1907) is Dmitry Mendeleev's Memorial Day, the creation of the first periodic table based on the atomic weights of the elements.
Dimitri Mendeleev was born on February 8, 1834, in Tobolsk, Siberia,
Russia, the 17th last son of Ivan Pavlovich Mendeleev and Maria Dimitrievna
Mendeleev. His father died when he was 13 years old. Mother's factory was
destroyed by fire. Mendeleev's family moved to St. Petersburg in 1849. There he
joined the Dmitry Teacher Training College in 1850 and graduated. Mendeleev
contracted tuberculosis in 1855 and had to move to Crimea in the Black Sea.
After a full recovery, he returned to St. Petersburg in 1857. Between 1859 and
1861 he was involved in chemical research in Heidelberg, Germany. In 1861 he
wrote and published a book on spectroscopy. The book was awarded the Demidov
Prize by the Petersburg Academy of Sciences. This earned him great fame.
In 1862 Mendeleev became a professor of chemistry at St. Petersburg
Government Technical College. In 1863 he became a professor at St. Petersburg
State University. He received his doctorate in 1865 for his study of the
combination of alcohol with water. In 1863 56 elements were known. At that time
the elements were discovered at a rate of about one per year. Other scientists
previously knew the definitions of molecules and the periodic properties of
elements. In 1864, John Newlands described the hexadecimal law, considering the
similarity that occurs when comparing eight elements into atomic weights. It
was published in 1865 as Newland's Eighth Law. Based on this new elements such
as germanium were identified. Until 1887 his discoveries were criticized
without being approved by the Chemical Society.
In 1864 Lothar Meyer proposed a concept of the periodic properties of
elements based on the parallel properties of 28 elements. But there are no
predictions about new elements in it. Mendeleev later became a teacher and wrote
a two-volume book, The Philosophy of Chemistry (1868-1870), for students. He
made it into a textbook for his curriculum. This book was written when he made
his most important discovery. When he tried to classify elements based on
chemical properties, the concept of the periodic table emerged, which predicted
periodic properties. When he got a lot of information about the atom, he
prepared an elementary table for himself. He said he had dreamed of that table
with all the elements.
"In my dream, I saw a table where all the elements were in their
proper place. I immediately got up and wrote it down on a piece of paper.
Unaware of previous work on periodic table preparation in the 1860s, he
prepared the table. The longitudinal periodic table was formed when other
elements were added in this manner. On March 6, 1869, Mendeleev submitted his
table to the Russian Institute of Chemistry entitled "The properties of
elements depend on their atomic weights". In it, he described both atomic
weight and covalence as elements that explain the properties of elements. He
completed the table by anticipating the properties of many undiscovered
elements in the table at the time. A few months after Mendeleev unveiled the
table, Julius Meyer of Germany announced a similar table.
If the elements are arranged in ascending order according to their
atomic weights, their properties will be revealed to be periodic. Elements with
similar chemical properties may have the same atomic weights (eg platinum,
iridium, osmium) or their atomic weights may be in sequence (eg potassium,
rubidium, cesium). The parallelism of the elements in a series in the order of
atomic weight varies according to their atomic weights. Similarly, to a
significant extent, they are similar to their unique chemical properties. It is
found in lithium, beryllium, boron, carbon, nitrogen, oxygen and fluorine.
Elements with low atomic weights are highly permeable. Atomic weight determines
the properties of elements, just as molecules determine the nature of a
substance. We should expect the discovery of many unknown elements (example:
two elements: similar to aluminium and silicon with their atomic weights ranging
from 60 to 75).
The atomic weights of the elements can sometimes be corrected by the
knowledge of the elements next to them. The atomic weight of tellurium should
be between 123 and 126, not 128. (The atomic mass of tellurium is 127.6, and
Mendeleev in a series assumed that the atomic weight should increase steadily).
Some characteristic properties of elements can be predicted by their atomic
masses. Dmitry Mendeleev published a periodic table of all known elements in a
Russian language scientific journal. He predicted many new elements that could
complete the table. A few months later, Meyer published a similar table in the
German Journal of Linguistics. Some consider Meyer and Mendeleev to be
co-creators of the periodic table. According to Mendeleev's table, based on the
properties of germanium, gallium and scandium, he accurately predicted the
properties of the undiscovered elements eco styling, aluminium and ecoperone.
He used the nicknames Eka, tie, and tri (one, two, three in Sanskrit)
for naming the eight elements that appeared in his calculation. Mendeleev
raised questions about some of the atomic weights of the elements accepted in
his time. (Atomic weights could only be measured with low accuracy at the
time). He pointed out that they did not correspond to the periodic rule
recommended by his timeline. He noted that tellurium has a higher atomic weight
than iodine. And he put them in the right order. The atomic weights accepted at
the time were predicted to be wrong. He was confused about where to place the
known Langhans. And predicted that atomic mass actinides would be in another
order in the same table. Some rejected Mendeleev's predictions that there were
more elements. But in 1875 and 1886 he proved that Ga (gallium) and Ge
(germanium) matched the properties specified in the blanks, respectively.
By giving Sanskrit names to elements on the list of "undiscovered
elements" according to his policy, Mendeleev expressed his admiration and
gratitude to the Sanskrit grammarians of ancient India. His work was a way of thanking
grammar scholars for inventing two-dimensional forms of basic sounds, the most
advanced principles of language. Mendeleev was a friend of the Sanskrit
Böhtlingk. At the time, Poutling was preparing the second edition of his book, Pāṇini.
Mendeleev wanted to honour Bowling by incorporating these into the nomenclature
for the elements.
When elements were at odds by atomic weight, Mendeleev gave priority to
homogeneity. (Example: In terms of atomic weight, although similar to the
elements nitrogen and phosphorus, the element magnesium is placed in the
beryllium family based on its properties). Their periodic characteristic
discoveries at both levels were later explained by the theory of internal
structure. The original draft, invented and developed by Mendeleev, will be
published many years later as a book entitled "Temporary Structure of
Elements". Dmitry Mendeleev is referred to as the father of the column
table. He refers to the instrumentation or table of information in his columns
and columns as the periodic system. It is a remarkable achievement that
Mendeleev defined the properties of elements not discovered in his time. Dmitry
Mendeleev, who developed the first periodic table based on the atomic weights
of elements, passed away on February 2, 1907, at the age of 72 in St.
Petersburg.
Source By: Wikipedia.
Information: Dr. P. Ramesh, Assistant Professor of Physics, Nehru Memorial
College, Puthanampatti, Trichy.
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