Atom History

5. a compound, no matter what its source, always contains definite, or constant, proportions of its elements by mass
8. Believed that all matter consisted of 4 elements: Earth, Fire, Wind, and Water.
11. English schoolteacher who developed a theory involving the relationship between matter and the atom.
13. Believed all matter was divisible to a point where no more division was possible.
14. As the theory of Quantum Mechanics has developed, it is now believed that electrons exist in an “AREA” not in a specific “path”.
15. The plum pudding model depicts the electrons as negatively-charged particles embedded in a sea of positive charge.

1. First began investigating the structure of the atom.
2. a modern framework for visualizing the submicroscopic behavior of electrons in matter.
3. Developed the “atomos” theory
4. states that when elements combine, they do so in the ratio of small whole numbers.
6. More established than Democritus.
7. Further experimented with Thomson’s model.Created the Gold Foil Experiment
9. Matter is made of tiny particles called atoms that can’t be subdivided.
10. the electrons encircle the nucleus of the atom in specific allowable paths called orbits
12. Suggested that instead of electrons moving in random motion that they actually followed a path around the nucleus.