1. Naming Binary Molecular Compounds
2 elements
covalent bond

2. 3 Rules to Name
1. Name the first element using the entire name 2. Second element in the formula- use the root word and end in –ide ex: Oxygen Sulfur Hydrogen
Oxide
Sulfide
Hydride

3. 3. Add a prefix to both words to indicate the number of atoms
mono hexa-
di hepta-
tri octa-
tetra nona-
penta deca-

4. Exceptions to the Rules
1. When the formula contains one atom of the first element, omit mono ex: CO2
Carbon Dioxide
Not: Monocarbon Dioxide

5. 2. Drop the final letter in the prefix if the element begins with a vowel - For prefixes 1 & 4-9 ex: CO
Carbon monoxide
Not: Carbon monooxide

6. Example 1
S4N2
tetra di
sulfur
nitride
nitrogen
tetrasulfur
dinitride

7. Example 2 SO3 tri oxygen sulfur tri oxide Only one atom of sulfur
- so no prefix needed
oxygen
sulfur
tri
oxide

8. Example 3
P4S5
penta
tetra
sulfur
tetra
phosphorus
penta
sulfide

9. Example 4 CO mono oxygen NOT monooxide carbon mon oxide
Only one atom of carbon
- so no prefix needed
oxygen
NOT monooxide
carbon
mon
oxide

10. Example 5 NH3 tri hydrogen More Common Name is “ammonia” nitrogen tri
Only one atom of nitrogen
- so no prefix needed
hydrogen
More Common Name is “ammonia”
nitrogen
tri
hydride

11. Example 6 CH4 tetra hydrogen More Common Name is “methane” carbon
Only one atom of carbon
- so no prefix needed
hydrogen
More Common Name is “methane”
carbon
tetra
hydride

12. Example 7-9 Example 7: As2O3 Diaresenic trioxide Example 8: N2O5
Dinitrogen pentoxide
Example 9: P4O10
Tetraphosphorus decaoxide