Dmitri Mandeleev (jan 16, 1869 – jan 25, 1869)
Description:
Arranged the elements in order of increasing atomic weight. However, he left gaps for elements that have not been discovered and swapped the order for several eelmentsso that the periodic pattern and their properteis can be seenAdded to timeline:
Date:
jan 16, 1869
jan 25, 1869
~ 9 days