Atoms- Atoms and the Periodic Table

Describe the structure of atoms in terms of neutrons, protons, and electrons and the role of the atomic structure in determining chemical properties.

400 B.C. - Democritus thought matter could not be divided indefinitely. • 350 B.C - Aristotle modified an earlier theory that matter was made of four “elements”: earth, fire, water, air. • Aristotle was wrong. However, his theory persisted for 2000 years. fire air water earth • This small particle he called “atomos”