1. All acids will end in the word “acid”. (ex. Hydrochloric acid)
For right now a compound is an acid if it STARTS WITH a H
Not always true in real life, but it will be for us at this moment in time.
All acids will end in the word “acid”. (ex. Hydrochloric acid)

2. When to include prefix “Hydro”
You use the “Hydro” prefix only when the formula includes hydrogen and one other element. (no polyatomic)
HCl = hydrochloric acid
Short Formula = Long Name
Always “Hydro(Insert element here)-ic Acid

3. When Not to Include “Hydro”
No Hydro prefix is used if there is a polyatomic Ion Present
HClO3 = chloric acid
Long Formula = Short Name

4. One last thing….
When naming acids with polyatomics, sometimes there are two ions with similar names: Ex) Nitrate and Nitrite
If the polyatomic ion ends in “–ate”, then the suffix “-ic” will be added.
Example – Nitrate  HNO3  Nitric Acid
If the polyatomic ion ends in “–ite”, then the suffix “-ous” will be added.
Example – Nitrite  HNO2  Nitrous Acid

5. Examples: H2S Polyatomic Ion?
the formula is “short”, so the name is long , hydro is needed.
What is the ending?
Hydrosulfuric acid

6. H2SO4
Polyatomic ion?
The formula is long, so the name is short
No need for “hydro”
What is the ending?
Name: Sulfuric acid

7. HNO2
Polyatomic ion?
The formula is long, so the name is short
no need for “hydro”
What is the correct ending?
Name: Nitrous acid

8. Writing Formula Help SOCS!
Find oxidation numbers (charges) and criss cross as you would with ionic compounds.
If name is long (includes Hydro) then it is the element hydrogen and another element from periodic table.
If the name is short, you have a polyatomic ion. Look for “ –ic” or “-ous” to determine which polyatomic ion to use.

9. Phosphoric acid
Name short- formula long (polyatomic)
use oxidation numbers to get the formula
H3PO4
Hydrophosphoric acid
long name- short formula – criss cross ox #
H3P
Phosphorus acid
Short name  Long formula (Polyatomic)
H3PO3

10. Practice! HF
HBrO3
H2CrO4
H3P
HClO2

11. Hydrosulfic Acid Acetic Acid Hydroiodic Acid Phosphoric Acid
Practice Writing!
Hydrosulfic Acid
Acetic Acid
Hydroiodic Acid
Phosphoric Acid
Chlorous Acid