History of the Atomic Model Democritus (400 BC) Democritus (400 BC)
Matter, Elements, and Compounds. Matter: Anything that takes up space and has mass. There are 92 naturally occurring elements, of these 25 are essential.
Author: Seymour Simon Genre: Expository Nonfiction Big Question: Why is it important to know about the universe?
History of the Atomic Model