John Dalton discovered that all matter is made of atoms, atoms are invisible and indestructible, all atoms of a given element are identical in mass and properties, compounds are formed of two or more different kinds of atoms, and a chemical reaction is a rearrangement of atoms.
Print his periodic table and put here
Dalton based his theories on the idea that only like atoms in a mixture of gases repel, whereas unlike atoms appear to react indifferently toward eachother
Lothar Meyer used atomic weights to arrange 28 elements into 6 families that bore similar chemical and physical characteristics, he discovered the valence, which was the number that represented the combining power of an atom of a particular element, was the link among each family of elements and the pattern at which each family is organized.
Dmitri Mendeleev discovered that when all the known chemical elements were arranged in order of increasing atomic weight, the resulting table displayed a recurring pattern, or periodicity, of properties within groups of elements.
These three scientists and chemists influenced and started the construction for the periodic table we see today, and more.