Development of the Atomic Theory

2. discovered the subatomic particle we know as the electron.
4. region inside the atom where electrons are likely to be found.
6. a charged particle resulting from the gaining of or the losing of an electron.
9. the sum of the protons and neutrons in an atom.
12. a particle that has no charge.
13. proposed that electrons move around the nucleus in definite paths.
14. The SI unit that describes the mass of a particle in an atom.
18. a force found in an atom.
20. a force found in an atom.
21. Each electron cloud exists at a certain_____.

1. suggested that elements combine in certain proportions because they are made of atoms.
3. a force found in an atom.
5. proposed model by Thomson suggesting that electrons were mixed throughout the atom.
7. protons, neutrons, and electrons are also referred to as...
8. a particle with a negative charge.
10. former student of Thomson who tested his theory by aiming a beam of positive charged particles at a she of gold foil.
11. an atom that has the same number of protons as other atoms of the same element do but that has a different number of neutrons.
14. smallest particle into which an element can be divided and still have the properties of an element.
15. the number of protons in the nucleus of an atom.
16. a force found in an atom.
17. a positively charged particle.
19. not able to be divided