1. (3.1) Classifying Chemical Compounds

2. Atoms can combine to form compounds of two bond types: Intramolecular – within the molecule  Ionic  Covalent ◦ Polar Covalent ◦ Non-Polar Covalent  Co-ordinate covalent ◦ Metallic Intermolecular – between molecules  Hydrogen Bonding  London Dispersion forces (LDF)  Dipole- dipole  http://www.mhhe.com/physsci/chemistry/ani mations/chang_7e_esp/bom1s2_11.swf http://www.mhhe.com/physsci/chemistry/ani mations/chang_7e_esp/bom1s2_11.swf Van der waals forces

3.  Physical properties  Ex: Solubility  high solubilityvs.low solubility  Chemical bonds form when the valence e - of atoms interact.  Atoms can either exchange or share electrons

4.  When 2 atoms exchange (or transfer) electrons 1 atom loses an e - 1 atom gains an e - metal non-metal lose gain

5.  form crystals  have high melting and boiling points  very hard and very brittle  conduct electricity when they dissolve in water or molten but not in the solid state

7.  When 2 atoms share electrons  Usually forms between two non-metals

8.  have much lower melting and boiling points than ionic compounds  soft and squishy (compared to ionic compounds, anyway)  more flammable than ionic compounds  don't conduct electricity in water.  Covalent compounds aren't usually very soluble in water.

9.  What type of bonding is present in the following? Draw Lewis diagrams to illustrate.  CaCl 2 H2OH2O  NH 3  AlCl 3  Ca 3 N 2  CO 2

10.  Electronegativity is a periodic trend that can be useful.  Defn: Electronegativity (EN) is a measure of an atom’s ability to attract electrons in a chemical bond.  When 2 atoms form a bond, each atom attracts the other’s electrons in addition to its own.

11.  As you go across a period, EN increases  As you go down a group, EN decreases  This trend can be summarized on your periodic table. radius metallic properties IE EA IE EA EN

12.  The difference between EN values (  EN) for the 2 atoms in a bond can be used to predict bond type.  Ex: CaF 2  EN =  Chemical bonds range from mostly ionic to mostly covalent.

13.  EN values 3.3 1.7 0.5 0 mostly polar mostly ionic covalent covalent

14.  Polar Bond: ◦ unequal sharing of electrons. One atom in the molecule draws electrons closer to itself. Example: HF has a polar bond because Fluorine atom is more electronegative and so it draws electrons CLOSER to itself, giving the bond polarity  Non-polar bond: ◦ PERFECT SHARING OF ELECTRONS

16.  If a molecule contains polar covalent bonds, the entire molecule may have a positive end and a negative end, in which case it would be classified as a polar molecule.  Not all molecules containing polar covalent bonds are polar molecules,  Carbon tetrachloride, CCl 4 (l), and HCl(g)  Molecules with non polar bonds are all non polar molecules

17. i) calcium fluoride  EN = CaF 2 ii) hydrogen chloride  EN = HCl iii) oxygen  EN = O2O2