Early 1800's -
The idea of protons and and electrons were not discovered until around the 20th century and so there were only two things that grouped the elements together in those times and this was;
- Physical and Chemical properties
- Atomic mass
and so the elements were arranged in order of atomic mass and when this was done there were noticeable links between the properties of elements to each other.
He was the first person to have a real go at trying to arrange the elements into some kind of…