1. Naming and Formula Writing
Covalent Compounds
Naming and Formula Writing

2. Covalent Compounds
Are made up of two NONMETALS. (Both elements are from the right of the step line (green elements shown)).

3. Prefixes you need to know
One – Mono
Two – Di
Three – Tri
Four – Tetra
Five – Penta
Six – Hexa
Seven – Hepta
Eight – Octo
Nine – Nona
Ten – Deca

4. Rules for Covalent Compounds
#1 – If the compound has only one atom of the first element (no subscript), we just name it normally (do not write mono….). If there are two or more atoms of the first element, we use a prefix to tell how many there are (the subscript).
#2 – For the second element, we ALWAYS use a prefix (even mono) and we change then ending of the element to –ide.

5. For Example… What would you call this compound: CO2? Carbon Dioxide
We do not call it Monocarbon Dioxide

6. Try these SiCl4 C3H9 SO2 N2O5 Silicon tetrachloride
Tricarbon nonahydride
Sulfur dioxide
Dinitrogen pentoxide
(you can drop off the –a from penta here so you don’t have to put two vowels together.)

7. Can you do it in reverse?
What is the chemical formula for Dinitrogen Monoxide?
N2O
Remember, when using prefixes, it tells you the actual subscript, you do not need to determine charges, or criss-cross, etc.

8. Try these… Carbon disulfide Dinitrogen monosulfide
Diphosphorus hexaoxide
Tricarbon octachloride
CS2
N2S
P2O6
C3Cl8