1. Chapter 8 Chemistry 1L Cypress Creek High School
Unit 8: Ionic Bonds
Chapter 8
Chemistry 1L
Cypress Creek High School

2. Part 2: Naming and Writing Formulas for Ionic Compounds

3. Ionic Bonds – Writing Formulas
Sodium and chlorine bond in a 1:1 ratio to form NaCl
Calcium and chlorine bond in a 1:2 ratio for form CaCl2
What determines each ratio & formula? ________________
oxidation numbers

4. Ionic Bonds – Writing Formulas
CRISS-CROSS METHOD
Oxidation numbers (excluding charge) of each ion trade places to become the subscripts in the formula – must be reduced to lowest whole number ratio; 1’s are not written
Ca & S
Ca2S2
Al & Cl
AlCl3
CaS 4

5. Ionic Bonds – Writing Formulas
Try to predict the ratio and resulting formula for each of the following ions based on their oxidation numbers:
Ions
Oxidation Numbers
Ratio
Formula
Magnesium & Oxygen
Mg2+ & O2-
1:1
MgO
Lithium &
Sulfur
Aluminum & Oxygen
Sodium & Phosphorus
Barium &
Fluorine
Li+ & S2-
2:1
Li2S
Al3+ & O2-
2:3
Al2O3
Na+ & P3-
3:1
Na3P
Ba2+ & F-
1:2
BaF2

6. Three Types of Ionic Compounds
We will learn how to write nomenclature for:
Binary Salts
2 elements: a metal and a nonmetal
Ternary Salts
3 or more elements
Includes a polyatomic ion
Salts with Multiple Oxidation Numbers
Can be binary or ternary
Includes a transition metal

7. Binary Salt Naming Contains 2 elements: cation & anion Naming:
Name the cation (no changes)
Drop the end of anion and add “ide”
Example: MgCl2 = magnesium chloride

8. Binary Salt Naming
We’ve already predicted these formulas. Now, try to predict the names for each binary salt:
Ions
Oxidation Numbers
Ratio
Formula
Name
Magnesium & Oxygen
Mg2+ & O2-
1:1
MgO
magnesium oxide
Lithium &
Sulfur
Li+ & S2-
2:1
Li2S
Aluminum & Oxygen
Al3+ & O2-
2:3
Al2O3
Sodium & Phosphorus
Na+ & P3-
3:1
Na3P
Barium &
Fluorine
Ba2+ & F-
1:2
BaF2
lithium sulfide
aluminum oxide
sodium phosphide
barium fluoride

9. Name
Formula
acetate
C2H3O2- or CH3COO-
ammonium
NH4+
carbonate
CO32-
chlorate
ClO3-
chlorite
ClO2-
chromate
CrO42-
cyanide
CN-
dichromate
Cr2O72-
hydrogen carbonate
HCO3-
hydroxide
OH-
hypochlorite
ClO-
nitrate
NO3-
nitrite
NO2-
perchlorate
ClO4-
permanganate
MnO4-
phosphate
PO43-
sulfate
SO42-
sulfite
SO32-
Polyatomic Ions
Some ions contain more than one element - called a polyatomic ion
The group as a whole has an overall charge
Examples:
Lithium and sulfate would bond together to make Li2SO4
Ammonium and sulfur would bond together to make (NH4)2S

10. Ternary Salt Naming
Contains 3 or more elements: cation & anion – most polyatomic ions are anions, only cation is ammonium (NH4+)
Naming:
Name the cation (no changes)
Name the anion (no changes)
Example: Na2SO4 = sodium sulfate
Exception: When ammonium is paired with an element anion
NH4Cl = ammonium chloride

11. Al & SO3 Al2(SO3)3 K & PO4 K3PO4 Ternary Salt Formulas
You must use parentheses if you have more than one polyatomic ion. Be sure to criss-cross the oxidation numbers and write it OUTSIDE of the parentheses.
Al & SO3
Al2(SO3)3
K & PO4
K3PO4 11

12. Ternary Salt Formulas & Naming
Try to predict the formulas and names for each ternary salt:
Ions
Oxidation Numbers
Ratio
Formula
Name
Potassium & Hydroxide
K+ & OH-
1:1
KOH
potassium hydroxide
Calcium & Carbonate
Barium &
Nitrate
Sodium & Phosphate
Ammonium & Sulfur
Ca2+ & CO32-
1:1
CaCO3
calcium carbonate
Ba2+ & NO3-
2:1
Ba(NO3)2
barium nitrate
Na3PO4
Na+ & PO43-
1:3
sodium phosphate
NH4+ & S2-
1:2
(NH4)2S
ammonium sulfide

13. Salts with Multiple Oxidation #s Naming
Transition elements can form more than one type of positive ion.
For example, copper can form both Cu+ and Cu2+ ions, and iron can form both Fe2+ and Fe3+ ions.
Zinc and silver are two exceptions – they only have one oxidation number
The zinc ion is Zn2+ and the silver ion is Ag+.
Naming:
Name the cation
Put the roman numeral representing the oxidation # of the metal in parentheses (do not indicate the charge)
Name the anion, changing the ending to “ide” (binary) or naming the polyatomic ion (ternary)
Example:
FeCl2 = iron (II) chloride
FeCl3 = iron (III) chloride

14. Salts with Multiple Oxidation Numbers Practice
Ions
Oxidation Numbers
Ratio
Formula
Name
Copper & Nitrate
Cu+ & NO3-
1:1
CuNO3
copper (I) nitrate
Lead &
Oxygen
Cobalt &
Hydroxide
Nickel & Phosphate
Chromium & Sulfur
Pb4+ & O2-
2:1
PbO2
lead (IV) oxide
Co3+ & OH-
3:1
Co(OH)3
cobalt (III) hydroxide
Ni2+ & PO43-
2:3
Ni3(PO4)2
nickel (II) phosphate
Cr2+ & S2-
1:1
CrS
chromium (II) sulfide