Английский язык, 9 класс

In 1869 the great Russian scientist Dmitri Mendeleyev announced the discovery of the Periodic Law of elements. So science received the key to the secrets of matter. All the greatest discoveries which have been made since then in the fields of chemistry and physics have been based on this law. But he is not only the scientist, who developed the periodic classification of the elements. Mendeleev carried on many other activities outside academic research and teaching. He was one of the founders of the Russian Chemical Society. He also worked as a professor, published his textbooks.