Explanation & Key Takeaways: • Dmitry Ivanovich Mendeleev is credited with the creation of the Periodic Table of Elements. • He arranged the elements in order of increasing atomic mass, which allowed for the prediction of the properties of elements that had not yet been discovered. • Mendeleev's periodic table was first published in 1869 and has been a fundamental tool in the field of chemistry. • The periodic table not only organizes elements based on their atomic mass but also by their chemical properties, which are repeated in 'periods'. Related Concepts: +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------+ | Fact | Detail | +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------+ | First Periodic Table | Mendeleev's first periodic table was published in 1869, featuring 63 known elements at that time. | | Predictions | Mendeleev predicted the existence and properties of elements that would fill gaps in his table, such as germanium, gallium, and scandium. | | Modern Periodic Table | The modern periodic table is arranged by atomic number rather than atomic mass, a change made after the discovery of isotopes. | | Legacy | Mendeleev's work laid the groundwork for the modern chemical industry and the way we understand chemical elements today. | +-----------------------+-------------------------------------------------------------------------------------------------------------------------------------------+