O ano de 1869 marca a descoberta do sistema periódico por dmitri mendeleev. O químico e físico russo criou a primeira versão da tabela periódica dos. Em 1869, quando o químico russo dimitri mendeleev publicou pela primeira vez sua tabela periódica de elementos químicos, ficou claro que as propriedades químicas e. Tal consagração se deveu ao seu trabalho relacionado à. Ciência dmitri mendeleev, o químico que ordenou a matéria o culminar das tentativas de ordenar os elementos químicos teve de esperar até um cientista russo.

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Mendeleev was both a teacher and an academic chemist, and in the early 1860s published a prize-winning textbook that placed him at the forefront of chemical education. He was, however, frustrated by the apparent disorder of the chemical elements so set about developing a way to classify them.

Other scientists had been trying to find ways to arrange the elements since at least the middle of the 18th Century. In 1864, just a few years before Mendeleev presented his periodic table, the British chemist John Newlands published his ‘Law of Octaves’ which classified the known elements into eight groups in order of their relative atomic masses. However, Newlands’ work was ridiculed at the time. His work was only formally recognised in 1887.

Mendeleev, meanwhile, was unaware of Newlands’ work because the Society of Chemists had refused to publish his findings. The Russian chemist therefore continued to work on his own system. Tradition dictates that he wrote the characteristics of the known elements on cards and played a game of ‘chemical solitaire’ with them. He apparently fell asleep during one of these card games and had a dream in which he saw the cards ‘fall into place’. Mendeleev realised that the features of the elements repeated in a predictable pattern, based on their atomic weight.

While Mendeleev’s approach led to there being some gaps or spaces in ‘periods’ where he believed an element should exist, he was able to calculate the missing element’s atomic mass and properties. His predications later turned out to be correct when missing elements such as gallium were discovered.

• 6th March 1869: Dmitri Mendeleev presents his periodic table to the Russian Chemical Society (Read More)