Mendeleev's Periodic Table of Elements
Definition - What does Mendeleev's Periodic Table of Elements mean?
Mendeleev's Periodic Table of Elements, published in 1869, was one of the first periodic tables of elements ever published and is widely considered the first periodic table that still somewhat resembles the periodic table used in modern times. The order of the elements in the table is determined by atomic mass.
Corrosionpedia explains Mendeleev's Periodic Table of Elements
Mendeleev's Periodic Table of Elements was named after Dmitri Mendeleev (1834 - 1907), a Russian chemist who discovered and developed the periodic law. The periodic law declares that elements, when arranged by their atomic mass, have properties that recur regularly. For his work creating order among the elements, Mendeleev received acclaim from the scientific community and many scientific awards.
While comprehensive at the time, Mendeleev's Periodic Table of Elements did not have all of the elements or order of modern periodic tables. Over 60 elements have been discovered since Mendeleev published his periodic table, not the least of which are helium and the other noble gases.
Mendeleev's Periodic Table of Elements left unfilled gaps for elements that had not yet been discovered; the modern periodic table has no such gaps. Also, transition elements are separated in modern periodic tables, whereas Mendeleev grouped the transition elements he knew of with all of the other elements. Lastly, Mendeleev organized the elements in his table by atomic mass and not atomic number, the latter being the way modern tables list the elements.