# Warm Up8-28-14 1.Find the volume of an object with 4 g/cm 3 and weight 40 g. 2.Explain why regular coke sink and diet coke float when placed in water 3.Water.

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Warm Up8-28-14 1.Find the volume of an object with 4 g/cm 3 and weight 40 g. 2.Explain why regular coke sink and diet coke float when placed in water 3.Water has a ratio of 2 Hydrogen atoms to 1 Oxygen atom. What law explain this? 4.Which part of Dalton’s atomic theory is false? Homework Aug 29 - Online HW Sept 3 – Element Project Bring pennies Agenda Turn in labs Test Chp 1 Notes Chapter 3-2 Element Project & Notebook

Test Chp 1 Do not write on the test Bubble your ID #, record your Version ID and Name on the answer document Multiple choice #1-24 Free response #25-26 – No calculators

Chapter 3-2 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 -Note: 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