HISTORY OF THE PERIODIC TABLE
In the EARLY 1800s - it was only possible to calculate atomic mass.
Newlands Law of Octaves - 1864
Arranged by ATOMIC MASS
Some patterns were identified - Alkali Earth Metals and Alkalis.
Messed up with Transition Metals - didnt get it right.
Mixed up metals and non metals.
Some groups didnt have similar properties.
NO GAPS WERE LEFT.
Dmitri Mendeleev - 1869
Arranged by both ATOMIC MASS & PROPERTIES
GAPS WERE LEFT TO KEEP SIMILAR PROPERTIES TOGETHER AND FOR UNDISCOVERED ELEMENTS. This was proven when the predicted elements were discovered, and…