Dmitri Mendeleev
Unaware of the earlier work on periodic tables going on in the 1860s, he made the following table:
By adding additional elements following this pattern, Mendeleev developed his extended version of the periodic table. On 6 March 1869, he made a formal presentation to the Russian Chemical Society, titled "The Dependence between the Properties of the Atomic Weights of the Elements", which described elements according to both atomic weight (now called "relative atomic mass") and valence. This presentation stated that
History of Western civilization
The 1859 publication of "On the Origin of Species", by the English naturalist Charles Darwin, provided an alternative hypothesis for the development, diversification, and design of human life to the traditional poetic scriptural explanation known as Creationism. According to Darwin, only the organisms most able to adapt to their environment survived while others became extinct. Adaptations resulted in changes in certain populations of organisms which could eventually cause the creation of new species. Modern genetics started with Gregor Johann Mendel, a German-Czech Augustinian monk who studied the nature of inheritance in plants. In his 1865 paper "Versuche über Pflanzenhybriden" ("Experiments on Plant Hybridization"), Mendel traced the inheritance patterns of certain traits in pea plants and described them mathematically. Louis Pasteur and Joseph Lister made discoveries about bacteria and its effects on humans. Geologists at the time made discoveries indicating the world was far older than most believed it to be. Early batteries were invented and a telegraph system was also invented, allowing global communication. In 1869 Russian chemist Dmitri Mendeleev published his Periodic table. The success of Mendeleev's table came from two decisions he made: The first was to leave gaps in the table when it seemed that the corresponding element had not yet been discovered. The second decision was to occasionally ignore the order suggested by the atomic weights and switch adjacent elements, such as cobalt and nickel, to better classify them into chemical families. At the end of the 19th century, a number of discoveries were made in physics which paved the way for the development of modern physics – including Maria Skłodowska-Curie's work on radioactivity.