1. 3.2- EXPLAINING MOLECULAR FORMULAS Molecular Substances

2. Different Terms  Molecular Substances belong to two groups  Molecular elements Two of the same non-metals O 2  Molecular Compounds Two different non-metals CO 2.

3. Molecular Elements  Due to their reactive nature, some elements will never be found as single atoms.  H 2, N 2, O 2, F 2, C l 2, Br 2, I 2  These can be explained with Lewis models  S 8 and P 4.  These are not easily explained via models

4. Molecular Elements (cont.)  Draw Lewis Models for F 2, H 2 and for N 2. OO O O O +

5. Structural Diagrams  To convert a Lewis Model into a Structural Diagram, replace each covalent bond (pair of shared electrons) with a dash.  Draw Structural Models for F 2, H 2 and for N 2. OO O=O

6. Types of Bonds  Covalent bonds can be  Single ( 1 pair of shared electrons )  Double ( 2 pair of shared electrons )  Triple ( 3 pair of shared electrons )  More bonds are stronger bonds

7. Determination of Ionic Formula’s  Given a metal & non-metal such as calcium and nitrogen you can “figure out” the product Ca 3 N 2 by “swapping charges” and simplest whole number ratios.

8. Determination of Molecular Formula  Given two non-metals you can not “figure out” the product. You either memorize or use the name.

10. Drawing Molecular Structures  Additional rules are needed to draw the more complex molecular structures.  Draw a molecular structure for C 2 H 6  Draw the electron dot diagram of the atom that has the highest bonding capacity.  Form shared pairs of bonding electrons with the remaining atoms.

11.  If any bonding electrons remain on adjacent atoms, form a double or triple bond.  In the finished electron dot diagram, all atoms (except hydrogen) should contain a stable octet.  Draw a structural diagram of the molecule.

12.  Page 85-90  Everything