1. Formulas and Names for Covalent Compounds
Ionic compounds bond in predictable proportions
Formulae for covalent compounds are hard to predict because 2 non-metals can often bond in different proportions
Eg. sulfur and fluorine combine to form:
SF4 OR SF6
We need a way to tell them apart

2. Naming Covalent Compounds
We add Greek prefixes to indicate the number of each element
Prefix
Number
mono- 1
hexa- 6
di- 2
hepta- 7
tri- 3
octa- 8
tetra- 4
nona- 9
penta- 5
deca- 10

3. Naming Covalent Compounds
Write the less electronegative element first with the correct prefix
Write the second element, with the correct prefix
Change the ending of the second element to “ide”, just like ionic compounds
Note:“mono-” is only used for the second element. If the first element has one atom, just use the element name

4. Examples: Name these covalent compounds
SCl2
SF4
SF6
N2O5
P2O3
P4O10

5. Formulas for Covalent Compounds
Use the prefixes to find the number of each atom present
Eg. disilicon hexabromide
Exceptions for covalent compounds
H2O = water
NH3 = ammonia
CH4 = methane

6. Examples: Give the formula for these covalent compounds
iodine monochloride
dinitrogen tetroxide
tricarbon disulfide
phosphorus pentachloride
silicon disulfide

7. Formulas and Names for Binary Acids
Binary Acids – contain H and one other element
Many are gases at room temperature
Only when dissolved in H2O do they become acids
Use the prefix “Hydro” + second element name + suffix “ic”, followed by acid
Eg. HCl(aq) = hydrochloric acid
Note: aq = aqueous Read as “in water”

8. Examples: Name these Binary Acids
HF(aq)
H2S(aq)
HBr(aq)

9. Formulas and Names for Ternary Acids
Ternary Acids contain oxyanions
Oxyanions – polyatomic anions with oxygen
Anions ending in “ate” change to “ic”
Anions ending in “ite” change to “ous”
Write “acid” after the anion name
When writing chemical formulas (aq) must be written after the formula

10. Examples HNO3 = nitric acid H2SO4 = sulfuric acid
HClO4 = perchloric acid
HClO3 = chloric acid
HClO2 = chlorous acid
HClO = hypochlorous acid

11. Examples: Name these Ternary Acids
HNO2
H3PO4
H2CO3