1. Molecular Compounds

2. What is a molecular compound? A molecular compound is a compound that is composed of only two elements held together by covalent bonds.

3. Most molecular compounds are made from nonmetals. Molecular compounds are more difficult to name because the atoms combine through covalent and not ionic bonds. Sometimes these compounds have generic or common names (e.g., H2O is "water") and they also have systematic names (e.g., H2O, dihydrogen monoxide).

4. Naming Molecular Compounds To name molecular compounds, prefixes are used to indicate the number of atoms in the molecule.

5. Prefixes Prefix Meaning mono- 1 di- 2 tri- 3 tetra- 4 penta- 5 hexa- 6 hepta- 7 octa- 8 nona- 9 deca- 10

6. EXAMPLE: N2O4 The prefix for 2 is di- and the prefix for 4 is tetra. The name tetraoxide should be shortened to tetroxide to make it easier to pronounce. N2O4 is named dinitrogen tetroxide.

7. EXAMPLE: PCl5 The prefix for 1 is mono-, but the name of the compound usually does not begin with the mono- prefix. PCl5 is named phosphorus pentachloride.

8. PRACTICE PROBLEMS: NO2 = _________________________ BF3 = _________________________ nitrogen trifluoride = _____________________  diphosphorus pentaoxide = ________________

9. Practice Problems 1. Antimony tribromide

10. 5. Iodine pentafluoride

11. 9. P4S5

12. 12. Si2Br6