He made Dobereiners triads which were a group of 3 elements that were similar to each other.
John Newland’s law of octaves was put forward after he arranged the elements then known into a table ordering them by relative atomic mass.
Mendeleev also arranged the elements into a table ordering them by relative atomic mass, but he arranged them so that elements which were similar were put into the same vertical columns in the table.
Meyer made his own table which was more sophisticated because he related atomic number and atomic volume.
William Ramsay discovered argon (jointly with Lord Rayleigh), helium, neon, krypton and xenon.
Rayleigh found the gas argon (Jointly with William Ramsay).