Writing Formulas for Covalent Compounds

Writing the formula for a non-ionic compound from its name is simply a matter of writing down what it says.

For example diphosphorus pentoxide would be written P₂O₅

Here are all the number prefixes that you need to know:

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

Just remember that if no number word is included (for the first element) then there is 1 of them. So nitrogen tribromide would be NBr₃
Try these on your own. The answers are here.

1. dichlorine monoxide
2. oxygen difluoride
3. boron phosphide
4. nitrogen trifluoride
5. sulfur tetrachloride
6. zenon trioxide
7. carbon dioxide
8. tetraphosphorus decoxide
9. phosphorus trichloride
10. sulfur dioxide
11. bromine pentafluoride
12. disulfur dichloride
13. boron triiodide
14. tetrarsenic decasulfide
15. silicon tetrabromide
16. krypton difluoride
17. boron trichloride