The correct answer is option 3. 1869.
Dmitri Mendeleev, a Russian chemist, and Lothar Meyer, a German chemist, both independently proposed versions of what would become known as the periodic law in 1869.
Their proposed periodic laws were based on the observation that when elements are arranged in order of increasing atomic weights, certain properties recur at regular intervals. Specifically, they noticed that elements with similar chemical properties tended to occur at regular intervals in this arrangement.
Mendeleev is often credited with the more widely recognized formulation of the periodic law because he not only proposed the idea but also created the first widely accepted version of the periodic table based on this concept. He arranged the elements in rows and columns based on their atomic weights and chemical properties, leaving gaps for elements that had not yet been discovered. Mendeleev's periodic table also allowed for the prediction of properties of these undiscovered elements.
Meyer's work was similar to Mendeleev's and provided independent support for the periodic law. He also arranged the elements in a table based on their atomic weights and noticed similar patterns to Mendeleev's periodic table.
Both Mendeleev and Meyer's contributions were crucial in the development of the modern periodic table, which forms the basis of our understanding of the organization of chemical elements and their properties. |
