1. HW: Read pages 460 - 461 Draw the Lewis structure, write the formula, and indicate the shapes for the following compounds: Silicon tetrabromide Hydrogen disulfide

2. Types of Covalent Bonds

3. Nonpolar Covalent bond Electron pair is shared equally among bonding atoms Bonding atoms have similar electronegativity values (difference 0.0 – 0.2)

4. Polar Covalent Bonds Unequal sharing of the electron pair between bonding atoms More electronegative element pulls the electrons more toward it and develops a partially negative (  -) side to the bond Less electronegative atom develops a partially positive charge (  +)

5. Are the bonds between the following atoms polar or nonpolar? If polar, which atom would be  + and which would be  - N and H H and O Br and Cl

6. How do the bonds that hold atoms together affect the molecules of that substance? The molecules themselves can be polar or nonpolar To determine whether a molecule of a substance is polar or nonpolar, we must look at the polarity of the bonds and the symmetry of the molecule.

7. Nonpolar molecules A nonpolar molecule has neither a positive or a negative end. - The electrons are equally distributed around the molecule. Molecules containing only nonpolar bonds, are always nonpolar. Ex) all diatomics Molecules containing polar bonds may be nonpolar molecules, if the polarity of the bonds is cancelled by symmetry. Ex) CO 2, CH 4

9. Polar Molecules (Dipoles) Molecules in which the electron cloud is unequally distributed around the molecule. Dipoles have both a positive and a negative side to the molecule. Dipoles are asymmetrical.

10. Ex) H 2 O, NH 3

11. Molecular Geometry Read pages: 455-456 Complete the Polarity Worksheet

12. VSEPR Theory Explains the shapes of molecules Due to the NEGATIVE charge of the electron pairs, molecules are shaped so that the valence electron pairs are as FAR APART as possible.

13. Linear MoleculesLinear Molecules (1) All compounds containing only 2 elements must be linear OR the atoms must have two areas of electron density around the central atom

14. TetrahedralTetrahedral (4) Shape that has 4 equal surfaces The angle between bonds is 109.5⁰ Central atom bonded to 4 different atoms

15. Pyramidal (5) Electron pairs are arranged in a tetrahedron around central atom Take pyramidal shape due to the presence of an unshared pair of electrons

16. BentBent (6) Angular shaped molecule 4 pairs of electrons around central atom are arranged in a tetrahedron two unshared electron pairs give bent shape