John Dalton

-law of constant proportions: dalton realized that all elements combine in constant proportions to form new substances. -billiard ball model: atoms are build similar to billiard balls. they are small, invisible particles. -first to make an atomic theory: 1. all matter is made of atoms 2. atoms of the same element are identical in every way 3. atoms of different elements are different 4. atoms are held together by an invisible force