1. Representing Compounds - Molecular
Molecular formula – shows the types and numbers of atoms combined in a single molecule of a compound
Ex. CO, H2O2, SO3, O2
Chemical formula – shorthand representation of the composition of a substance using atomic symbols and numerical subscripts

2. Representing Compounds - Molecular
Structural formula – shows kind, number, arrangement, and bonds (single, double, or triple) of the atoms in a molecule (or polyatomic ion)

3. Representing Compounds - Molecular
Structural formula – indicates kind, number, arrangement, and bonds of the atoms in a molecule
Ex.

4. Representing Compounds - Molecular
Lewis structures - diagrams that show valence e- as dots, the inner e- and nucleus are included in the letter symbol for the element being represented

5. Representing Compounds - Molecular
Lewis structures
Reminder…
Group 1

6. Representing Compounds - Molecular
Lewis structures
Reminder…
Group 2

7. Representing Compounds - Molecular
Lewis structures
Reminder…
Group 13

8. Representing Compounds - Molecular
Lewis structures
Reminder…
Group 14

9. Representing Compounds - Molecular
Lewis structures
Reminder…
Group 15

10. Representing Compounds - Molecular
Lewis structures
Reminder…
Group 16

11. Representing Compounds - Molecular
Lewis structures
Reminder…
Group 17

12. Representing Compounds - Molecular
Lewis structures
Reminder…
Group 18

13. Representing Compounds - Molecular
Lewis structures
Structures of individual elements may be joined to form compounds
pairs of dots (or a dash) between symbols represent bonds (or electron pairs), dots adjacent only to one symbol are unshared e-

14. Representing Compounds - Molecular
Lewis structures…
Lone (unshared) pair of e- – pair of e- that is not involved in bonding, but instead belongs exclusively to one atom

15. Representing Compounds - Molecular
Lewis structures
Ex. F2, NH3, H2O, CH4, O2, CO2, N2, CH2O, C2H2, PI3
(must draw structures)

16. Representing Compounds - Molecular
Lewis structures
Octet exceptions:
Less than full octet
Ex: Boron compounds such as BF3

17. Representing Compounds - Molecular
Lewis structures
Octet exceptions:
More than full octet – atoms beyond 2nd period, most often S & P (extra e- go to 3d level)
Ex: SF4