1. Chapter 14 Liquids and Solids

2. Three types of bonding between atoms Covalent – electrons shared between nonmetal atoms, forms molecules or covalent crystal lattice structures such as diamond (covalent network solid) Ionic bonds – transfer of electrons between metals and nonmetals, forms ionic crystal lattice structures (ionic solid) Metallic bonds – group sharing of loosely held electrons of metals, These electrons can migrate throughout the metal.

3. Highest Boiling Point – crystal lattice structures (ionic or covalent) Lowest Boiling Points – molecular compounds

4. Crystal lattice structures DiamondSalt

5. Molecular compounds Molecules attracted to each other by: –Hydrogen bonding (strongest) –Dipole-dipole attraction (next strongest) –Dispersion forces (weakest, therefore lowest boiling point)

6. Hydrogen bonding The hydrogen of one molecule is “semi-bonded” to a non-bonding pair of electrons of another molecule.

7. Requirements for hydrogen bond 1.molecule must have hydrogen 2.molecule must have a non-bonding pair of valence electrons (check electron-dot structure) HF, H 2 O, NH 3 all have hydrogen bonding, strongest intermolecular force (high melting points)

8. Dipole-Dipole Forces Is the attraction of the positive side of one molecule to the negative side of another molecule. Molecule must have a dipole for this to occur For dipole must have –Polar covalent bond –A geometry that allows for a dipole

9. Dispersion Forces Attraction between non-polar molecules that have a temporary dipole Created by a temporary induced warping of the electron cloud. Also called London dispersion forces or van der Waals forces Is weakest of all intermolecular forces (very low boiling points)

10. Change of state A liquid boils when the vapor pressure (partial pressure) is equal the atmospheric pressure. Boiling can be thought of as internal evaporation. For a bubble to form internally it must be able to overcome atmospheric pressure.

12. Water can be made to boil at a lower temperature by decreasing the pressure above it. Triple point – temperature and pressure at which a substance will exist as a solid, liquid and a gas at the same time.

13. Phase diagram of water

14. Phase-change graph

15. Bonds and energy Breaking molecular or weak bonds between molecules always takes energy. The formation of any bond always gives off energy. At high temps there is enough energy in the system so bonds cannot form. (different temps for different bonds)

16. Assignment Page 492 and 493 questions 3, 4, 8, 9 – 13, 15, 17, 20, 21, 24, 25, 28, 30, 31, 33