1. Take the next 5-10 minutes to complete the water mini-lab
Take the next 5-10 minutes to complete the water mini-lab. After seeing what happens, write 3+ sentences explaining what you saw and what you think this has to do with the concept of polarity.
Warm-Up 1/10/14

2. Attractions Between Molecules: Intermolecular Forces
Friday 1/10/14

3. Summary: Bonds Between Atoms
Types: Ionic, Covalent (polar and nonpolar)
Electrons are being shared or transferred between ATOMS.
Summary: Bonds Between Atoms

4. How are molecules held together
How are molecules held together?? There must be something, or materials would never stick together.

5. Intermolecular Forces
Inter: Between, Molecular: Molecules
Forces that attract molecules to other molecules. These include:
Dipole-dipole attraction
Hydrogen bonding
London dispersion forces
Intermolecular Forces

6. NOTE: Intermolecular Forces are NOT bonds
NOTE: Intermolecular Forces are NOT bonds!!!! Friends don’t let friends make this mistake!!

7. Dipole-Dipole Attraction
Attraction between oppositely charged regions of neighboring POLAR molecules.
Dipole-dipole attraction in hydrogen chloride, a gas that is used to make hydrochloric acid

9. Hydrogen Bonding: A Special Type of Dipole-Dipole
Attractions between the semi-positive H atoms with the semi-negative N, O, and F atoms.
Ex) Base pairing in DNA by hydrogen bonding

10. Hydrogen Bonding in Water

11. Hydrogen bonds are very strong.
Evidence: High boiling point of water and high surface tension

12. London Dispersion Forces
Temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles
Electrons are in constant motion, so atoms can have areas that are temporarily + or -
This type of force is always present for all categories of molecules (polar or not)

14. The strength of LDFs is proportional to a molecule’s size (weight)
These are the only forces of attraction between completely nonpolar molecules
The strength of LDFs is proportional to a molecule’s size (weight)
Large nonpolar molecules may have substantial dispersion forces
Small nonpolar molecules have weak dispersion forces and exist almost exclusively as gases

15. More LDFs

16. What intermolecular forces exist between ammonia (NH3) and water (H2O) molecules?
Always exists for all molecules: _________________
Is it polar? What does that mean?
Does it have the correct atoms for H-Bonding?
Example

17. Complete questions 1-6 on the Intermolecular Forces Worksheet
Complete questions 1-6 on the Intermolecular Forces Worksheet. (We will finish the rest another day)
Reminder: Quest next Wednesday
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