Transcript Notes Unit 2-2

Warm Up
9-3-15
1. Write an equation to solve for volume.
2. Explain why regular coke sink and
diet coke float when placed in water
3. Express 0.000 000 6988 in scientific
notation
4. Water has a ratio of 2 hydrogen atoms to 1
oxygen atom. What law explain this?
Agenda
Test Unit 1
Notes Unit 2-2
Element Project & Notebook
Homework
Sept 4 – Element Project
Bring pennies
Test Unit 1
• Multiple choice #1-25
• Free response #26-27
– No calculators
• Do not write on the test
• Bubble your ID #, record your Version ID and
Name on the answer document
Unit 2-2
Structure of Atoms
Thompson’s Experiment
• J.J. Thompson a physicist that created the CRT
(cathode-ray tube)
• To study current
Thompson’s Experiment
CRT
• cathode electrode has negative charge
• anode has positive charge
• Glowing beam come from the cathode end
• Deflected by a magnet = beam has a charge
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
Thompson’s Experiment
• “Plum Pudding” atomic model
Rutherford’s Experiment
• Rutherford conducted gold-foil experiments
and discovered the nucleus.
Gold-Foil Experiment
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
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.
Current Atomic Model
• Changes to Dalton’s atomic theory
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Assignments
• Notes Summary
• Turn in notebooks
• Bring pennies