1. Naming Compounds & Writing Formulas

2. Naming Ionic Compounds
Ionic compounds form between a metal and a nonmetal.
The metal forms a cation (+ ion) and the nonmetal forms an anion (-ion).
The cation is always named first and is the element name.
The anion is always named second – the root of the element name with an –ide ending.

3. Examples:
LiCl
BeF2
Al2O3
Ca3P2
NaBr
K2S

4. Writing Formulas of Ionic Compounds
Determine the charge on the cation and anion
Balance the charges (so that the net charge on the compound is neutral) to write the formula.

5. Sodium chloride Lithium oxide Beryllium fluoride Aluminum sellenide
Examples:
Sodium chloride
Lithium oxide
Beryllium fluoride
Aluminum sellenide
Strontium arsenide

6. Naming Covalent Compounds
Covalent compounds form between two nonmetals.
Numerical prefixes tell how many atoms of each element there are.
The first nonmetal gets the prefix and name of the element
The second nonmetal gets the prefix and an –ide ending.

7. Numerical Prefixes 1 = mono 6 = hexa 2 = di 7 = hepta 3 = tri 8 = octa
4 = tetra 9 = nona
5 = penta 10 = deca
If there is only one atom of the first element, the name does not get a prefix

8. Examples:
N2O4
BF3
P4S3
As2Cl6

9. Writing Formulas Covalent Compounds
Write the element symbols for each nonmetal
Put a subscript after each symbol, based on the prefix

10. Examples: Carbon dioxide Trisilicon heptacarbide
Pentaiodine octafluroide
Nonabromine monophosphate