1. Determining Formulas The Criss-Cross Method
Examples
Na+1 + O-2 
Ca+2 + P-3 
C+4 + O-2 
Na2O
Ca3P2
C2O4  reduced to CO2

2. deduce a chemical formula.
Naming Compounds
Chemical Nomenclature--> system used to name chemical substances.
The Name of a compound indicates the composition of the substance.
From the name one can
deduce a chemical formula.

3. Naming Binary Compounds
The first element is named as usual but only a stem of the second is used followed by the suffix “ide”
For example: MgCl2 is Magnesium chloride
: Al2O3 is Aluminum Oxide
The Chlorine and Oxygen must change their suffix from “ine” and “ygen” to “ide” !

4. Naming Compounds Try these! NaCl Li3N MgI2 Sodium Chloride
Lithium Nitride
Magnesium Iodide

5. Stock System for Transitional Metals
A compound that contains a transitional metal must be named so that the oxidation # of the metal is identified.
A Roman numeral is placed after the metal. It represents the oxidation # of the metal.
Ex. FeCl3  Iron (III) Chloride
CuCl2  Copper (II) Chloride

6. Assigning Oxidation # Transitional Metals
The total charge on any compound or molecule
is always equal to zero.
To determine unknown oxidation #s, add up the oxidation #s of the Cation and Anion and set them equal to zero. (Create an algebra formula and solve for X.)
Example Cr2O3 total charge = 0
Cr = x , O = -2
Formula 2x + 3(-2)= 0  2x-6= 0 x= +3 Cr= +3

7. Naming Transitional Metal Compound
Name These,
FeCl2
CrO2
NiP
Iron(II) Chloride
Chromium(IV) Oxide
Nickel(III) Phosphide

8. Common Names  The old naming system Latin Names
Antimony Sb
Stibium
Copper Cu
Cuprum
Gold Au
Aurum
Iron Fe
Ferrum
Lead Pb
Plumbum
Mercury Hg
Hydragyrum
Potassium K
Kalium
Silver Ag
Argentum
Sodium Na
Natrium
Tin Sn
Stannum
Tungsten W
Wolfram

9. Naming Molecules (Using prefixes)
If two non-metals are bonded covalently, the name can be shown using prefixes.
The number of atoms for each element in a molecule is usually indicated by the prefix:
mono atom - hexa atoms
di atoms - hepta atoms
tri atoms - octa atoms
tetra atoms
penta atoms

10. Naming Molecules Examples: nitrogen dioxide is NO2
dinitrogen pentoxide is N2O5
phosphorus tribromide is PBr3
The prefix represents the subscript.
 If the subscript is one mono is not needed.

11. Use Old Naming system and Stock system
Binary Molecules
Name these :::
Use Old Naming system and Stock system
PCl3
PCl5
SO2
Phosphorus TriChloride
Phosphorus(III) Chloride
Phosphorus PentaChloride
Phosphorus(V) Chloride
Sulfur Dioxide
Sulfer (IV) Oxide

12. Poly-Compounds
Formulas of compounds containing polyatomic ions are written in a manner to stress the fact that the ions are independent units
An example is Sodium Nitrate which contains the nitrate ion (NO3)-1 is written NaNO3

13. Pg 226 lists many more poly-atomic ions
Formula
Name
(NH4)+1
Ammonium
(C2H3O2)-1
Acetate
(ClO3)-1
Chlorate
(CN)-1
Cyanide
(OH)-1
Hydroxide
(HCO3)-1
Bicarbonate
(NO3)-1
Nitrate
(CO3)-2
Carbonate
(CrO4)-2
Chromate
(O2)-2
Peroxide
(SO4)-2
Sulfate
(PO4)-3
Phosphate
Poly-atomic ions Two or more atoms covalently bonded but as a group carry a charge.
Pg 226 lists many more poly-atomic ions
Memorize ions.
all 12

14. Poly-Compounds
When naming these compounds the name of the poly-ion is unchanged.
Examples
1. Na2SO4  Sodium Sulfate
2. (NH4)2Se  Ammonium Selenide
If Ammonium is the poly-atomic ion, the non-metal still maintains its “ide” suffix.

15. Poly-Compounds
If a compound contains a polyatomic ion with a subscript of two or more the ion is enclosed in parenthesis:
Example:
calcium bicarbonate Ca(HCO3)2
ammonium sulfide (NH4)2S

16. Memorize the 12 Common Poly-atomic Ions.
Poly-Compounds
Name these ::: Go to page 226 or your packet for help.
Ca(ClO3)2
NH4OH
Cr(SO4)2
Memorize the 12 Common Poly-atomic Ions.
There will be an Ion quiz very soon.
Calcium Chlorate
Ammonium Hydroxide
Chromium(IV) Sulfate

17. Oxy-Ions
Polyatomic Ions containing Oxygen can be represented a number of different ways.
If one less Oxygen in the formula. The suffix is changed from “ate” to “ite”. The ion’s charge does not change.
Ex. (NO3)-1  Nitrate vs. (NO2)-1  Nitrite
If two less Oxygens the prefix “hypo-” is placed in front of the “ite” name.
Ex (ClO)-1  hypo- Chlorite
If one more Oxygen the prefix “per-” is placed in front of the “ate” name.
Ex (ClO4)-1  Per Chlorate

18. Acids
Acids have their own naming system and they must be recognized when dealing with nomenclature.
The name acid comes from the Latin term for “sour”
{Acids are sour to the taste}
Acids are substances that donate protons (H+)
{usually when dissolved in water}
The Chemical formula almost always begins with Hydrogen
Example: hydrochloric acid  HCl
sulfuric acid  H2SO4

19. Naming Acids Lets separate acids into 2 types: H3PO4 H2SO4 HNO3 H2O
Acids that contain oxygen
H3PO4 H2SO4
HNO3 H2O
Acids that do not contain oxygen
HCl HBr
HF H2S

20. Naming Acids For acids containing “-ate” anions:
Naming acids containing oxygen:
For acids containing “-ate” anions:
Use root of the anion (for sulfate, SO42-, use sulfur)
Add “-ic” suffix then end with “acid”
Example: H3PO4 is Phosphoric acid
For acids with “-ite” anions:
Use root of the anion (for sulfite, SO32-, use sulfur)
Add “-ous” suffix then end with “acid”
Example: H2SO3 is sulfurous acid

21. Naming Acids (cont.) Naming acids not containing oxygen:
Add “hydro-” prefix to beginning
Use root of the anion (i.e. Cl- use chlor)
Add “-ic” suffix then end with “acid”
Example: HCl is hydrochloric acid
Name the following acids: HF
HNO2
HCN
H3PO4

22. Hydrate Molecules
A hydrate molecule is a ionic compound that contains water molecules trapped inside the crystalline structure.
The Formula includes a dot followed by the number of water molecules
Ex: Copper(II) Sulfate Pentahydrate
CuSO4 · 5H2O

23. Hydrate Molecules The Name of a hydrate molecule would
include two separate names.
To name, use the name of the ionic compound followed by the term … hydrate. A Greek Prefix would be used to represent the number of water molecules that are trapped.
CoCl2 · 2 H2O
Colbalt(II) Chloride Dihydrate