1. To Do… OWL Lectures Discussion Chapter 10 due Friday, March 30
Chapter 11 due Friday, April 6
Lectures
Continue reading Chapter 11
Discussion
Chapter 10 and Chapter 11 text homework

2. Clicker Question
Is the freezing of water an endothermic or exothermic process? (The system is underlined.)
A) endothermic
B) exothermic
C) neither

3. Big Ideas – Periodic Table
Originally arranged by atomic mass (protons not discovered).
See Co & Ni; Te & I.
Separated as “metals” and “nonmetals” (appearance/properties)
Chemical reactivity

4. Big Ideas – Periodic Table
The closer together the elements on the periodic table, the more chemically alike they are.
Especially true for elements in the same column.
“Missing” elements were predicted.

5. Big Ideas – Models Models are not reality.
We use different models for different reasons.
A model should be as simple as possible, but not simpler (Einstein)
To answer more questions, the model must be more complex.

6. Various Atomic Models (Ch. 4)
Dalton: Indivisible atoms
J.J. Thomson: Atoms emit tiny negative particles. (Therefore atoms not indivisible!)
Rutherford: Some α-particles bounce back when shot at atoms. (There is a concentration of mass with a positive charge in the atom.)

7. Water vs liquid nitrogen