Download I CAN write Chemical formulas

I CAN WRITE & NAME
CHEMICAL FORMULAS
BY…
1. Write the oxidation number above each element.
2. Cross
the oxidation numbers and write the
oxidation number (without plus or minus) of one
element as the subscript of the other element.
3. Reduce the subscripts (number of atoms) to their
simplest form, if needed.
WHAT IS THE CHEMICAL FORMULA FOR
CALCIUM CHLORIDE?
Check transition metals & metalloids to see if they have a different oxidation charge than
what you expect from the periodic table by reversing the criss cross over method.
Formula
Name
AgCl
Fe2(SO4)3
Lead (V) oxide
Cobalt (III) nitrate
CrBr3
Iron (III) oxide
Silver (I) acetate
If the charge is different then use (Roman numeral) after the metal
to clarify the charge.
I know to use prefixes ONLY when there are 2 _____________ in the formula.
#
1
2
3
4
5
6
7
8
9
10
prefix
formula
CO
CO2
I2P5
N3O7
SiCl4
name
• SiCl4
• CO2
• NH3
THE FOLLOWING SLIDES ARE SOME EXAMPLES
DONE FOR YOU TO REVIEW BY QUIZZING
YOURSELF & CHECKING HOW YOU DID ON THEM:
1. Write the oxidation number above each element.
2. Cross these and write the oxidation number (without plus or minus
charge) of one element as the subscript of the other element.
+1
Li
-2
O
+2
Ba
-3
N
Lithium oxide
Barium Nitride
=
Li2O
=
Ba3N2
+2
Mg
-2
S
Magnesium Sulfide =
MgS
+1
K
-1
Cl Potassium Chloride =
KCl
+1
Na
-1
I
Sodium Iodide =
NaI
1. Write the oxidation number above each (putting parantheses around
the polyatomic ion).
2. Cross these and write the oxidation number (without plus or minus
charge) of each ion as the subscript of the other atom/polyatomic ion.
+1
Na
-1
(OH) Sodium hydroxide =
+2
Ca
-2
(CO3) Calcium carbonate
CaCO3
=
+2
Zn
-3
(PO4) Zinc phosphate
+3
Al
-1
(NO3) Aluminum nitrate
+1
(NH4)
NaOH
Zn3(PO4)2
=
=
-2
=
Ammonium
sulfite
(SO3)
Al(NO3)3
(NH4)2SO3
Ionic compounds contain a + charged part & a – charged part:
Li2O
= Lithium oxide
Ba3N2
= Barium Nitride
If – part is a single element
then change ending to -ide
CaCO3 = Calcium carbonate
Al(NO3)3 = Aluminum nitrate
(NH4)2S
= Ammonium sulfide
If there are more than 2
capital letters then find the
polyatomic ion (do not change
the ending on polyatomic ions
just on single elements at the
end that are not part of the
polyatomic ion
1. NaCl = Sodium Chloride
2. K2O =
Potassium Oxide
3. I2F3 =
diiodine trifluoride
4. Fe2O3= Iron (III) Oxide
5. CuCl =
Copper (I) Chloride
6. NaOH = Sodium Hydroxide
7. AlPO4 =
Aluminum Phosphate
8. Mg(NO3)2 = Magnesium Nitrate