14 sept 1869 año - Dmitri Mendeleev - Classification of Elements (1869)

Descripción:

Mendeleev classified elements into 7 groups according to their atomic mass and found a correlation between atomic mass and the properties of an element. He arranged elements into a diagram called the Periodic Table. The table created by Mendeleev also alotted spaces for elements that hadn't been discovered yet and were found later in history.