Naming Binary Molecular Compounds 2 elements covalent bond

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. Add a prefix to both words to indicate the number of atoms mono- 6. hexa- di- 7. hepta- tri- 8. octa- tetra- 9. nona- penta- 10. deca-

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

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

Example 1 S4N2 tetra di sulfur nitride nitrogen tetrasulfur dinitride

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

Example 3 P4S5 penta tetra sulfur tetra phosphorus penta sulfide

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

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

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

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