1. Do Now & Announcements Complete notes (first page)—mostly review
When done with first page, you may start the activities at the 3 stations
You must use your observations and your knowledge of intermolecular forces to come up with the definitions in the boxes
Unit 5 Test ~FRI 3/20

3. 3. Intermolecular Forces
Forces of attraction between molecules
(dotted lines represents attraction between molecules)

5. Intermolecular Forces & Phase of Matter
For the same chemical substance, molecules in the SOLID phase will have stronger intermolecular forces between them than molecules in the GAS phase

6. Pressure:
Atmospheric Pressure=pressure exerted by the air above a surface
Vapor Pressure=pressure exerted by the molecules at the surface of the liquid; (they want to escape to the gas phase)
VAPOR
ATMOSPHERIC

7. VAPOR
ATMOSPHERIC
Boiling point of a liquid: vapor pressure = atmospheric pressure

8. : VAPOR PRESSURE = ATMOSPHERIC PRESSURE =NORMAL BOILING POINT
- - - STANDARD ATMOSPHERIC PRESSURE also = 1 atm
: VAPOR PRESSURE = ATMOSPHERIC PRESSURE
=NORMAL BOILING POINT

9. Becoming a Gas (Add to Notes)
A higher vapor pressure  will evaporate more easily and go into the gas phase
For a liquid to boil, the vapor pressure (↑) must overcome the atmospheric pressure (↓) (the particles in the liquid phase are “breaking free” as they change into the gas phase!)

10. **If you live in Denver, Colorado, you often have to adjust cooking instructions. Why does water boil at a different temperature if you’re at a higher altitude (where the atmospheric pressure is lower)?