jan 1, 1869 - Mendeleev
Description:
He created an organized system of elements called the periodic table of elements. He used and referenced the system of organizing by atomic mass and the system of properties that were already being used by scientists at the time. He was also influenced by the first international chemistry conference (1860) that determined the weight of hydrogen as 1.Added to timeline:
Date:
jan 1, 1869
Now
~ 157 years ago