2.  Atoms are small hard particles made of a single material that can’t be divided.  Developed his ideas by thinking

3.  All substances are made of atoms  Atoms cannot be created, divided or destroyed  Atoms of same element are exactly alike  Atoms join together to make new substances  Developed his ideas using observations from experiments

4.  Small particles inside the atom  These particles have a negative charge  Present in every kind of atom  Developed his theory doing experiments with a cathode-ray tube

5. Thomson’s experiment

6.  Atom is mostly empty space  Tiny part is highly dense matter that is positively charged  Named this dense part the nucleus  Developed his theory doing his gold foil experiments

7. Rutherford Experiment Modern Version

8.  Electrons move around nucleus in certain paths  These paths are energy levels  Electrons can jump from one level to another.  Developed ideas by experimenting to see how atoms react to light

9.  Electrons do not travel in definite paths  Electron’s path can’t be predicted  Regions where electrons are likely to be found  These regions are known as electron clouds

10.  Particle in nucleus with protons ◦ Mass about the same as a proton ◦ No charge  Particle is called Neutron