1. Chemical Nomenclature
Sodium chloride NaCl
Carbon dioxide CO2
Copper(II) chloride CuCl2
Chemical Nomenclature
Naming compounds and
writing the formulas of compounds

2. 3 Sets of Rules of Naming Rules
Class or Type I - Ionic Bond between metal predictable + charge and a negative nonmetal or polyatomic ion ; name cations, anion ends in “ide”
Examples: NaCl – sodium chloride ; MgCl2, magnesium chloride
Class or Type II- Ionic Bond with variable oxidation state transition metal; Roman numerals used to specify charge of transition metal
Example: CuCl2 – copper(II) chloride
Class or Type III – Covalent bonds between Two nonmetals; uses prefixes
Example: CO2 – carbon dioxide; N2O4 – dinitrogen tetroxide

3. Location of First Element in Formula determines class rules+1
Class or Type I +2 +3
Class or Type II
Class or Type III +1 +2

4. Location of First Element in Formula determines class rules+1
Class or Type I +2 +3
Class or Type II
Class or Type III +1 +2

5. Location of First Element in Formula determines class rules+1
Class or Type I +2 +3
Class or Type II
Class or Type III +1 +2

6. Elements: Sodium = Na and Chlorine = Cl
Class or Type I - Ionic Bond between metal with a predictable + charge and a negative nonmetal or polyatomic ion
Elements: Sodium = Na and Chlorine = Cl
Compound Formula: NaCl Name: sodium chloride
Elements: Sodium = Na and Oxygen = O
Compound Formula: Na2O Name: sodium oxide
Elements: Aluminum = Al and Bromine = Br
Compound Formula: AlBr3
Name: aluminum bromide

7. Class or Type I Compounds
Class or Type I - Ionic Bond between metal with a predictable + charge and a negative nonmetal or polyatomic ion
Rules for Naming Class or Type I Compounds
Name metal cation (positive + ion) first using element name;
Name nonmetal anion (negative – ion 2nd); change element name of anion to ends in “ide”
 Example #1: NaCl = elements: sodium and chlorine ;
Change chlorine → chloride
Ans: sodium chloride
Example #2: MgCl2
magnesium chloride
Link to 2-5 Key

8. Practice - Name the following compounds:
AlCl3
ZnBr2
Ga2O3
aluminum chloride
zinc bromide
gallium oxide
Link to 2-5 Key

9. Writing Formulas for Class I Compounds
Use location on periodic table to find charge for each element
Sum of charges must be zero.
If + charge ≠ - charge, use “Criss-Cross” technique
Final subscripts must be simplest ratio.

10. Example #1: (+ charge on cation = - charge on anion)
What is the formula of potassium bromide?
K = group 1 = lose 1 valence e- to fill outer level → +1 ion
Br = Group 7 = gain 1 valence e- to fill outer level → -1 ion

11. What is the formula of potassium bromide?
→ [K]+
Charges must balance in final formula.
K Br -1 → KBr

12. Example #2: (+ charge on cation ≠ - charge on anion)
What is the formula of calcium nitride?
Ca = group 2 = lose 2 valence e- to fill outer level → +2 ion
N = Group 5 = gain 3 valence e- to fill outer level → -3 ion

13. What is the formula of calcium nitride?
Charges: Ca+2 N-3
Criss-Cross move charge #
(ignore + or – ) to subscript on opposite ion
Ca+2 N-3
Final Answer: Ca3N2

14. Conceptual basis of “criss-cross”
Total + must = total - ; Least common multiple
(3) (+2) = (-3) = -6
Ca+2 Ca+2 Ca+2 = N-3 N-3 = -6
N -3
N -3
Ca +2
Ca +2
Ca +2

15. Practice- write formulas for the following compounds
Magnesium sulfide
Mg+2 S-2 →
Aluminum oxide
Al+3 O-2 →
Potassium sulfide
K+1S-2 →
MgS (simplest ratio)
Al2O3
K2S