Who is Dmitri Mendeleev, and what was his contribution to chemistry?
Dmitri Mendeleev was a Russian scientist credited with creating the first periodic table. He arranged all of the known elements in order of increasing atomic mass. He placed the elements in rows and columns so that elements with similar properties would be located together. He left blank spaces in his periodic table where no known elements seemed to fit. He explained that these blank spaces represented elements that had not yet been discovered, and based on their position in the periodic table, Mendeleev was able to predict the properties of these undiscovered elements. When these elements were discovered, their properties were very similar to those predicted by Mendeleev.
