Unit 02 B

1. Unit 02 B IMFA, liquids, solids, solutions, colligative properties

2. Intermolecular Attractions Van Der Walls Forces

3. Dispersion Forces • Dispersion forces are caused by the movement of electrons • Strength of attraction is determined by quantity of electrons • Example: Halogen family • Chlorine and Fluorine are gases @ STP due to their low number of electrons • Bromine has sufficient electrons to produce a liquid @ STP • Iodine is solid @ STP

4. Dipole Interactions • Dipole interactions are the attraction betweens the opposite poles of polar molecules • Hydrogen bonds are a especially strong of dipole interaction

5. Hydrogen Bonding • Hydrogen Bonds, the strongest of the intermolecular forces involves the attraction of molecules through the dipole created by the bond between a Hydrogen and a very electronegative atom

6. Colligative Properties • The properties of a solution that depend only on the number of solute particles per solvent molecule • Molality = moles of solute/kilogram of solvent

7. Freezing Point Depression • Freezing point of a solution is lowered with the addition of a solute, usually quite small • ∆Tf =Kfm • ∆Tf = freezing point depression m=molality,Kf=molal freezing point constant

8. Boiling Point Elevation • Adding a solute to a solution increases the temp. at which it boils • ∆Tb =Kbm

9. Metallic and Ionic Solids Structure

10. Simple Cubic • 1 net atom per unit cell • Cell edge = 2r

11. Body Centered Cubic • 2 atom per unit cell • Cell diagonal = 4r = (√3)(Length of Edge)

12. Face Centered Cubic • 4 net atoms per unit cell • Cell diagonal = (√2)(length of edge)

13. The End?