Today is the 182nd birthday of Dmitri Mendeleev, and Google has decided to honor him with one of their trademark "doodles". Mendeleev might not be a household name, but his work had such a fundamental impact on chemistry that he deserves to be universally known.
Mendeleev was a Russian chemist famous for the creation of periodic law, the construction of the periodic table and the prediction of properties of known elements, as well as the existence of elements that were yet to be discovered.
Born in Siberia in 1834, Mendeleev studied in St. Petersburg and worked in both physics and chemistry. He became a Doctor of Science in 1865 and achieved tenure in 1867. He published his magnum opus, Principles of Chemistry, in two volumes in 1868 and 1870.
He was not the first person to guess that elements had some periodicity; John Newlands and Lothar Meyer both suggested so in the years before Mendeleev's big breakthrough. However, Mendeleev realized some fundamental laws of the universe that still hold true today.
He formulated the law of periodicity, realizing that lighter elements are more abundant. He worked out that once the atomic weight of an element is known, then one can predict its properties and the type of bonds it forms. The law also allowed Mendeleev to predict the existence of eight elements unknown at the time, as well as the properties of three of them (germanium, gallium, and scandium).
The idea to summarize all the consequences of periodic law in the periodic table is probably his greatest contribution to science. According to A.A. Inostrantzev, a close friend of Mendeleev, he went three days and nights without sleep to work out the table. He finally fell asleep from extreme fatigue, but completed the table as soon as he woke up.
“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,” Inostrantzev claimed Mendeleev to have said afterward.
The periodic table is one of the most useful tools in chemistry. It arranges all the known elements in order of increasing atomic number (the number of protons), electron configurations, and recurring chemical properties. It is divided into 18 groups (columns) and 7 periods (rows), and it includes 118 elements. The first 94 elements occur naturally, while the remaining 24 are synthesized in laboratories.
While we know enough about the chemical and physical properties of elements to potentially produce a different version of the periodic table, the traditional structure is so ingrained in popular science that it has remained the standard layout around the world, used for both educational and comedic purposes.
Periodic table of elements which includes the country of discovery, by Jamie Gallagher, Public Engagement Officer for the University of Glasgow.
The success of the periodic table is not just due to familiarity. Although it contains a large amount of information, it is organized so simply that people can quickly grasp the principle behind it without having to possess an in-depth knowledge of chemistry.
Mendeleev's success was in bringing order to the elements. He gave chemistry a schematic way to be universally understood. The periodic table is 147 years old, and yet it is still being updated with new elements. Now that the 7th row is completed, scientists are looking to start the 8th, confident that the law discovered by Mendeleev will still be valid.