1. Mission B5 - How do you Name and Write chemical formulas for Compounds?
“Not Just James Bond”

2. Part 1 - Naming Binary Compounds
Binary compounds – elements with only two types of atoms in it
Naming binary compounds is simple
It is based on the names of the cations and anions and all binary compounds end in -ide
Examples:
NaCl = sodium chloride
CaF2 = calcium fluoride
Al2O3 = aluminum oxide
BaO = barium oxide 2

3. Part 2 - Naming Transition Metal Compounds
Similar to naming binary compounds
But transition metals have multiple oxidation states (can have different charges)
Steps
determine the oxidation number of the nonmetal
use the rules of oxidation states to solve
The name must have Roman numerals to show the oxidation state of the metal 3

4. Therefore CuCl2 is called copper II chloride
Example: CuCl2
Step 1
determine the charge on the chlorine
Chlorine has a higher EN therefore will be a negative oxidation state which is -1
But there are two chlorines so the total is -2
Step 2
Determine the charge on the copper
The compound’s total charge must equal zero
Copper must be a +2 charge to balance the chlorine
Therefore CuCl2 is called copper II chloride 4

5. what is the charge on the chlorine?
Example: In FeCl3
Step 1
what is the charge on the chlorine?
-1 = it has the higher electronegativity and is negative
What is the total charge of 3 chlorines?
-3 = 3 x -1
Step 2
what is the charge on FeCl3?
Zero = charges in compounds add up to 0
What is the charge on the iron then?
+3 = chlorine’s -3 + iron’s +3 = 0
What is the name of the particle FeCl3 then?
iron III chloride = “III” shows the iron’s charge 5

6. Part 3 - Naming Polyatomic Compounds
Polyatomic ions
Groups of atoms that have a collective charge on them
See CRTable E
Similar to binary naming
If more than two elements in the compound, look up the polyatomic ion on Table E
Example
[Na] [SO4] 2- Na2SO4
sodium + sulfate = sodium sulfate 6

7. Naming Polyatomic Compounds
Examples
Na2CO3
= sodium carbonate
HCN
= hydrogen cyanide
KClO3
= potassium chlorate
NH4Cl
= ammonium chloride 7

8. Part 4 - Naming Molecular Compounds
Naming molecular compounds (covalently bonded substances) is similar to naming ionic ones with one exception:
When naming substances with all nonmetals
Prefixes are used to designate the number of atoms of each
Prefix
# of Atoms
Formula example
Name
mono 1 CO
Carbon monoxide di 2
CO2
Carbon dioxide
tri 3
SO3
Sulfur trioxide
tetra 4
CCl4
Carbon tetrachloride
penta 5
PCl5
Phosphorus pentaflouride

9. Examples of Naming Covalent Compounds
CO - carbon monoxide
CO2 - carbon dioxide
SO2 - sulfur dioxide
N2O3 - dinitrogen trioxide
SF6 - sulfur hexafluoride
H2O - dihydrogen monoxide

10. When writing chemical formulas
Writing Formulas
When writing chemical formulas
Reverse the rules for writing chemical names
Here are examples of each type of chemical formula
Ex 1 - Binary compound - sodium chloride
sodium’s oxidation number is Na+1
chlorine’s oxidation number is Cl-1
Charges are equal and cancel each other
Therefore the chemical formula = NaCl 10

11. Writing Chemical Formulas
Ex 2 - Binary compound - aluminum chloride
one aluminum has is Al+3
one chlorine is Cl-
It takes one Al+3 to balance the charge of three Cl-
Therefore the formula for aluminum chloride is AlCl3
Ex 3 - Transition metals – iron II oxide
one iron II has a charge of Fe+2
one oxygen has a charge of O-2
The two charges balance out to a 1:1 ratio
Therefore the formula for iron II oxide is FeO 11

12. Writing Chemical Formulas
Ex 4 - Nonmetal-nonmetal compounds - dinitrogen trioxide
Oxidation numbers aren’t required in writing this formula
Dinitrogen is two nitrogens
Trioxide is there oxygens
Therefore the formula for dinitrogen trioxide is N2O3 12

13. Writing Chemical Formulas
Ex 5 - Polyatomic ions – magnesium nitrate
Magnesium (Mg+2) is in Group 2 and has a +2 oxidation charge
Nitrate (NO3-) is a polyatomic ion from Table E with an oxidation number of -1
So two nitrates are needed to balance the one magnesium and give a zero charge
Therefore the formula for magnesium nitrate is Mg(NO3)2 13

14. Writing Chemical Formulas
Ex 6 - Polyatomic ions and transition metals – copper I sulfate
Copper (Cu+1) has a +1 charge as per the Roman numeral
Sulfate (SO4-2) is a polyatomic ion from Table E with an oxidation number of -2
So two coppers are needed to balance the one sulfate and give a zero charge
Therefore the formula for copper I sulfate is Cu2 SO4 14

15. Writing Chemical Formulas
A short cut – the Criss-Cross method of writing
Look at the oxidation states of the elements in the compound
cross the numbers, drop the charges, and you will have the formula
Example – lead II chloride
Lead +2 charge
Chlorine charge
Pb Cl -1  Pb1Cl2