1. Warm Up 9-8-17 Express 0.000 000 6988 in scientific notation
Water has a ratio of 2 hydrogen atoms to 1 oxygen atom. What law explain this?
Which part of Dalton’s atomic theory is no longer true?
Pass out Periodic table
Video DE - Chemistry Basics: Atomic Theory and the Periodic Table Lab Conservation of Mass? Check Conservation of Mass lab at the end of class with summary
Agenda
Mystery box observation
Notes Unit 2-2 Turn in Archimedes’ Lab
Homework
Next Class – Bring pennies
Sept 14 – Quiz unit 2

2. Unknown Structure Activity
Purpose: Determine how the strings are attached on the interior of the box
 Observations: Draw a picture of how the strings are attached inside the box
Build it: Use strings, a styrofoam cup, scissors to build a model of the mystery box

3. Answer These Questions in Your Notebook
What were the challenges?
How did the model on your paper compared to the actual model that you created?
How did you know what’s inside the box even though you can’t see it?

4. Unit 2-2 Structure of Atoms

5. Thompson’s Experiment
J.J. Thompson a physicist that created the CRT (cathode-ray tube)
To study current
Experimented in 1887
CRT – airless glass tube, modifications lead to the the development of modern TV in 1928,
Pointilism - Seurgat

6. Thompson’s Experiment
CRT
cathode electrode has negative charge
anode has positive charge
Deflected by a magnet = beam has a charge
Magnet and TV demo Glowing beam come from the cathode end

7. Thompson’s Experiment
The Electron
The CRT beam moved a paddle
wheel
Electron consists of particles that
have mass and a negative charge
-Read only: e- are negatively charged but atoms have no charge, therefore atoms must contain + charge to balance the charges

8. Thompson’s Experiment
“Plum Pudding” atomic model
Discovered
Think it
exists

9. Rutherford’s Experiment
Rutherford conducted gold-foil experiments and discovered the nucleus and confirm the existence of protons.
Rutherford, a former student of Thompson disproved the plum pudding model in 1909

10. Gold-Foil Experiment
2 years later he came up with an explanation of what he observed

11. Rutherford’s Experiment
Only a positively charged particle could repel the positively charged alpha beam
The mass of this particle has to be larger than the incoming beam to deflect it
Most of the atom is empty space that’s why only some beams were deflected

12. Subatomic Particles The nucleus is made up of protons and neutrons
Proton: has a positive charge
Electron: has negative charge
Neutron: no charge.
A neutral atom has no net charge, means # of protons = # of electrons.
- ATOMS BILL NYE The radius of the atom is more than 10,000 times bigger than the nucleus
Nucleus is like a marble in the middle of a football stadium
Proton’s mass is 2000 times heavier than electrons

13. Changes to Rutherford Model
Neutron added to the nucleus
Discovery of subatomic particles - smaller parts that make up an atom:
Electrons (-), protons (+), and neutrons (0)

14. Assignments
Summary: Compare Thompson’s experiment to Rutherford’s experiment. Which subatomic particle did each person discover?
Finish & Turn in lab today
Work on worksheet 2-2 taped, glued or stapled in the notebook
Bring pennies next class (2-3 pennies)

16. Advertisement For Your Element
Element Advertisement Poster assignment (creative, color picture, slogan)
Subway – eat fresh
Just do it, I’m loving it