Dmitri Ivanovich Mendeleev was a Russian chemist born in 1834 who is best known for creating the first version of the periodic table of elements in 1869. He arranged the 63 known elements based on their atomic masses and properties, leaving gaps for elements not yet discovered. His periodic table was a breakthrough that allowed prediction of new elements and brought order to how elements were organized and understood. The modern periodic table still follows Mendeleev's groundbreaking work but has been expanded and refined over time as new elements were discovered.

1. Dmitri Ivanovich Mendeleev

3. He was a Russian Chemist

4. Born on February 8, 1834

5. The youngest child of either seventeen, eleven or fourteen.

6. Parents were Ivan Pavlovich Mendeleev and Maria Dmitrievna Kornilieva

7. His father died of tuberculosis at age 16Mendeleev’s Biography

8. Mother died of exhaustion Mendeleev died in St. Petersburg, Russia on February 2, 1907 Dmitri died at age 72 from influenza Biography Cont.

9. Studied at St. Petersburg and graduated in 1856 Published a book named “Principles of Chemistry” in 1869, in which he talks about the periodic table and how they are based on the atomic mass. Aftergraduating from St. Petersburg he was appointed to a professorship. Before he returned to teach at St. Petersburg, he went to Heidelberg where he opened his own laboratory. Three years after being appointed to a professorship he succeeded to the chair in the University. He was considered one of the greatest teachers of his time. Education & Work

10. Interests Besides his interest in chemistry, Mendeleev was interested in Art, Education and Economics.

11. The Periodic Table The sixty-three known elements were arranged based on ascending order of atomic weight and grouping them by similarity of properties. He predicted that they’re were three more yet to be discovered elements because when arranging the elements on the periodic table, he realized there were gaps in between. Ekaboron, Ekaaluminium, and Ekasilicon.

12. The advantage Mendeleev’s table had over previous attempts was that it not only exhibited similarities in small units such as triads, but it also showed similarities in an entire network of vertical, horizontal and diagonal relationships. He realized that by arranging the element cards in order of increasing atomic weight that certain types of elements regularly occurred. Scientific Method

13. In 1895, Rayleigh reported the discovery of a new gaseous element named argon. Ramsey followed by discovering the remainder of the inert gases and positioning them in the periodic table. But as mentioned earlier, there were also three more elements discovered while creating the periodic table. In 1914, Henry Moseley figured out each atomic number for the elements. He also was able to change the periodic law, which Mendeleev set up, and so place elements in the correct places on the periodic table. New Discoveries

14. Scientists produce and study new elements. Through this type of discovery, more can be learned about the forces that hold things together and what can break them apart. Significance

15. The periodic table used today is not the same as the one set up by Mendeleev. Besides adding new elements, British scientist Henry Moseley changed the use of atomic weight to the atomic number for arranging the elements. Moseley in 1913 published his work showing that the wavelength of X-ray emissions from elements matched the ordering of elements through the use of the atomic number. This new ordering eliminated the difficulties of the Mendeleev table. Modern Periodic Table

16. Modern Periodic Table The End