The document discusses the history and development of atomic theory from ancient Greek philosophers to modern atomic structure. Some key points covered include: - Democritus first proposed the idea of atoms in ancient Greece but lacked evidence. - In the 1800s, Dalton proposed his atomic theory that elements are made of atoms that combine in simple whole number ratios. - Advances revealed atoms have internal structure including a tiny dense nucleus and orbiting electrons. - Atoms are identified by their atomic number and mass number, which indicate protons, neutrons, and isotopes. - The mole, molar mass, and Avogadro's number allow relating masses to numbers of atoms and particles.

1. The Atom Building Block of Matter

4. Law of Conservation of Mass “ Mass is neither created nor destroyed during ordinary chemical reactions or physical changes.”

5. Law of Definite Proportions “ A chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound.”

6. Law of Multiple Proportions “ If two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers.”

7. Dalton’s Atomic Theory

10. Modern Atomic Theory

12. Atomic Structure