NAMING AND WRITING FORMULAS FOR
COMPOUNDS
Unit 4
1. NAMING IONIC
COMPOUNDS
• Ionic Compound:
• Composed of ions
• Cations & Anions
• Metals & Nonmetals
Cations:
• + charge
• Metals
• + Polyatomic Ions
Anions:
• - charge
• Nonmetals
• - Polyatomic Ions
1. Name the cation (always 1st)
2. Name the anion – add “ide” ending
(always 2nd)
If anion is polyatomic, just use name (no
ending)
* This is for cations with a single charge (oxidation state)
• For cations with more than one oxidation state
• Name the cation
• Add roman numeral to indicate charge of the
cation
2. WRITING THE FORMULAS
FOR IONIC COMPOUNDS
1. Write the cation symbol
2. Write the anion symbol (or polyatomic formula)
3. Balance + and – charges so they add to zero
3. NAMING AND WRITING
FORMULAS FOR
MOLECULAR COMPOUNDS
• Molecular Compounds
• Nonmetals only
• Use greek prefixes to tell
# of atoms
1 – mono
2 – di
3 – tri
4 – tetra
5 – penta
6 – hexa
7 – hepta
8 – octa
9 – nona
10 - deca
4. ACIDS
• Recognizing an acid
• Molecular compound beginning with “H” (or H2
or H3)
• May contain polyatomic ions
Binary Acids
1. Start name with “hydro”
2. Use anion name adding “ic” ending
3. End with “acid”
Oxyacids
1. Use polyatomic ion name
1. Add “ic” in place of “ate”
2. Add “ous” in place of “ite”
2. End with “acid”
Writing Acid Formulas
1. Write the symbol for hydrogen 1st
2. Write the symbol for nonmetal or polyatomic
anion
3. Balance + and – charges so they add to zero
• (H will have a charge of +1)
5. DIATOMIC MOLECULES
• 2 of the same atom bonded together
• Some elements naturally exist as diatomic
H, N, O, F, Cl, Br, I
6. HYDRATES
• Ionic salt with molecules of water attached
Naming Hydrates
1. Name the ionic compound
2. Use a greek prefix for number of water
molecules
3. End with “hydrate”
Writing the Formulas for Hydrates
1. Write the formula for the ionic compound
2. Indicate the number of water molecules with big
number in front of H2O
7. COMPOUNDS WITH
COMMON NAMES
1. H2O
2. NaHCO3
3. H2O2
4. NH3
5. CH4
6. HCH3COO (HC2H3O2)