1. Chapter 3: Atoms, the Building Blocks of Matter

2. Atomic Theory has Evolved! Leave a few lines to write what we discuss in class!

3. Law of Conservation of Mass Mass is neither created nor destroyed during an ordinary chemical reaction or physical change. Combustion of a Candle: C 25 H 52 + O 2 + E CO 2 + H 2 O + C + E

4. Class Demo Leave half a page

5. Pioneers of the Atomic Theory Chapter 3 Observant people have been looking at matter and pondering why different phenomenon occur for hundreds of years.

6. Early Philosophers Didn’t agree!!

7. Dead Dude #1- Democritus Ancient philosopher- 460BC Matter is made of indivisible particles. Atomos means “that which cannot be further broken down”

8. Shortcomings It is a conceptual definition, not based on science. Doesn’t talk about subatomic particles.

9. Dead Dude#2- Dalton Explained the Laws John Dalton (early 1800s) Atom is a solid, indestructible mass (like a billiard ball)

10. All Atomic Theory builds on Dalton’s Law 1. All matter is made of tiny particles called atoms. 2. All atoms of a given element are identical in size, mass and properties Atoms of each element are different. 3. Atoms cannot be subdivided, created or destroyed. 4. Compounds consist of atoms of different elements combined together. Compounds have constant composition (fixed ratio of atoms). 5 Chemical reactions involve the rearrangement of those atoms.

11. What did experiments with the cathode ray tubes teach us? http://www.youtube.com/watch?v=O9Goysc bazk&safety_mode=true&persist_safety_mo de=1&safe=active

12. Leave a few lines….

13. Dead Dude #3 J.J Thomson- 1850 A ball of positive mass containing a number of electrons that are embedded. Getting the idea that there are protons and electrons (nucleus).

14. Shortcomings Doesn’t explain the existence of electrons outside the nucleus or their importance in bonding. No neutrons- can’t explain radioactivity or the existence of isotopes.

15. Late 1800’s Discovery of and experiments using the cathode ray tube led to our understanding of the electron.

16. Millikan Oil Drop Experiment We will watch a video in class You may want to draw a picture We learned what the actual charge of an electron is– pretty cool!

17. Henri Becquerel- 1897 Researched newly discovered X- rays (Phosphorescence). Accidently discovered that uranium emits radiation that could be measured using photographic plates. Discovered Radioactivity- electrically charged particles.

18. The Dr’s Curie- 1898 Discovered new elements- Polonium and Radium. Very unstable elements that give off energy. This led to an under- standing of Alpha, Beta and Gamma particles.

19. Dead Dude #4 Rutherford Model- 1905 –Mass of the atom is concentrated in the center of a positively charged region called the nucleus. –The Planetary Model

20. Gold Foil Experiment- Draw this and write about the experiment.

21. We will watch a video here Leave room to describe the experiment in your own words.

22. Shortcomings Doesn’t place the electrons. Doesn’t include neutrons.

23. Bohr Model-1920 Believed that electrons traveled in precise orbits around the nucleus of an atom

24. Schrodinger Quantum Mechanical Model. Describes mathematically the wave properties of electrons and other very small particles The nucleus is at the center of the atom and the electrons are in the electron cloud.