1. Naming & Writing Formulas
Ch 5 - Ionic Compounds
Naming & Writing Formulas

2. Remember usually In an ionic compound Naming is EASY PEASY!
1st element is a + metal ion
2nd element is a – nonmetal ion
Naming is EASY PEASY!
1st element’s name doesn’t change
2nd element’s name ends in –ide
Transition metals need to show Roman Numeral
polyatomic ions keep their own names

3. Naming Nonmetal Anions

4. Transition Metals – Use Systemic Name

5. What are Polyatomic Ions
Groups of elements that act as a group
The charge is on the entire group
NEVER change formula of polyatomic ions
Put them in parenthesis if need be.
is written as SO4 -2
Ex. compounds: BaSO Barium Sulfate
Fe2(SO4)3 Iron III Sulfate

6. Common Polyatomic Ions

7. Examples 1. Regular 2. Transitional Metals 3. Polyatomic Ions
NaF – Sodium Fluoride
CaO – Calcium Oxide
2. Transitional Metals
FeCl3 – Iron III Chloride (Fe+3 because 3 Cl- in formula)
CuI – Copper I Iodide (Cu+1 because one I- in formula)
3. Polyatomic Ions
BaSO4 – Barium Sulfate
NH4OH – Ammonium Hydroxide

8. Mixed Practice BaI2 Ca(OH)2 FeCO3 Na2Cr2O7 Cu(ClO4)2 Barium iodide
Calcium hydroxide
Iron (II) carbonate
Sodium dichromate
Cupric perchlorate

9. Writing Ionic Formulas
Compounds are neutral: +ions & – ions have to balance
Steps
Write the + ion first
Write the – ion second
Compare oxidation numbers (charges)
If the same, you are done
If different, criss-cross as subscripts
Never change polyatomic ions (use parenthesis if needed)

11. Formula of Ionic Compounds
Al2O3
Al3+
O2-
CaBr2
Ca2+
Br-
Na2CO3
Na+
CO32-

12. Try it out…
Write the formula for a combination of these ions:

14. Try it Out
Write the formula of these ionic compounds: