1. I. Intermolecular and Intramolecular Forces section 2 Ch. 13 - Liquids & Solids C. Johannesson

2. Forces within a molecule (between atoms) Some covalent bonds are broken more easily than others Strength depends on distance (bond length) Size of atoms Number of shared electron pairs As the number of shared pairs increases, bond length decreases Shorter bond=stronger bond Triple bonds shortest, strongest C. Johannesson Intramolecular Forces

3. Intermolecular Forces Attractive forces between molecules a.k.a. van der Waals forces weaker than intramolecular forces C. Johannesson

4. B. Types of IMF C. Johannesson

5. B. Types of IMF London Dispersion Forces C. Johannesson View animation online.animation

6. London Dispersion Forces Weak forces that result from temporary shifts in the density of electrons in electron clouds When 2 nonpolar molecules are in close contact, the electron cloud of one molecule repels the electron cloud of the other molecule Changes the shape of the other C. Johannesson

8. Dipole-Dipole Forces Attractions between oppositely charged regions of polar molecules C. Johannesson + + - - View animation online.animation

9. Dipole-Dipole Forces Polar molecules have a permanent dipole and orient themselves so that oppositely charged regions match up. Stronger than dispersion forces If molecules being compared are similar in mass. C. Johannesson

10. Hydrogen Bonding Occurs when H is bonded to F, O, or N Creates a large partially positive charge on the H which is then attracted to the partially negative atom on another molecule C. Johannesson

11. C. Determining IMF NCl 3 polar = dispersion, dipole-dipole CH 4 nonpolar = dispersion HF H-F bond = dispersion, dipole-dipole, hydrogen bonding C. Johannesson