500
1) Each element is composed of tiny, indestructible particles called atoms
2) All atoms of a given element has the same mass and other properties
that distinguish them from atoms of other elements
3) Atoms combine in simple, whole–number ratios to form molecules
4) In a chemical reaction, atoms of one element cannot change into atoms
of another element
• They simply rearrange the way they are attached
Dalton's Atomic Theory