A step towards modern chemistry

Eight decades after the launch of known systematic attempts to arrange elements scientifically by a chemist, Dmitri Mendeleev, a Russian chemist, announced his periodic table to the Russian Physico Chemical Society on March 6, 1869.

In comparison to the contemporary number of elements as 118, only 63 elements had been discovered by the time Mendeleev announced his periodic table with arrangement of elements based on atomic weight depicting a regular pattern in chemical behaviour. Considered a landmark achievement in science, Mendeleev is recognised as the ‘Father of the Periodic Table’.

What made Mendeleev most popular among chemists trying to arrange elements in order was his wisdom in leaving gaps in the table for elements with predictable properties, but yet to be discovered. His predictions proved to be correct when such elements were discovered. Gallium (1875), Scandium (1879) and Germanium (1886) verified Mendeleev’s predictions.

Mendeleev is also credited with achievement to create a crucial tool for chemists to understand the relationship between elements and predict their reaction with each other, serving as a foundation stone for modern chemistry.

Though ‘hit and trial’ will be an inappropriate concept for illustrating Mendeleev’s attempt to arrange and rearrange elements, he used a method inspired by solitaire to arrange cards representing elements into periodic tables. He created a set of cards, one of each of 63 elements. He wrote the atomic weight and properties of elements on the card and continued to arrange and rearrange them until he arrived at the final creation.

Mendeleev impacted the world significantly by developing the periodic table, which allowed scientists to predict the existence and properties of undiscovered elements. Though the modern periodic table is based on the atomic number of elements, denoting number of protons in nucleus, Mendeleev’s creation in 1869 presented elements in ascending order of atomic mass, total number of neutrons and protons.

German chemist Lothar Meyer also produced a version of periodic table similar to Mendeleev’s in 1970. Like Mendeleev, he also left gaps for undiscovered elements, but did not predict their properties. The Royal Society of London awarded the Davy Medal in 1882 to both Mendeleev and Meyer. Mendeleev was also a recipient of the Copley Medal (1905) and Demidov Prize (1862).

The 101st element discovered in 1955 was named 'Mendelevium' in his honour. He was accorded special recognition five years ago when UNESCO named 2019 as the International Year of the Periodic Table to mark the 150th anniversary of Mendeleev’s publication.

“The Periodic Table of Chemical Elements is more than just a guide or catalogue of the entire known atoms (elements) in the universe, it is essentially a window on the universe, helping to expand our understanding of the world around us,” UNESCO wrote on its website.

Researchers and educators worldwide celebrated the occasion to highlight the importance of the periodic table and spread awareness about it in classrooms, workshops and seminars. People were encouraged to make use of the knowledge of the periodic table to solve issues in education, science and technology, agriculture, environment and health.

The youngest of over a dozen siblings, Mendeleev was born at Tobolsk in Russia on February 8, 1834, and died at Saint Petersburg in Russian on February 1, 1907.