Chemistry Nomenclature
Binary Ionic Compounds
What are they made of?
Binary  2 elements
Ionic metal ion + non-metal
ion
+  metal
sodium,
Na
Example 
chlorine, Cl-  nonmetal
REMEMBER !
• Metals tend to Lose electrons and
become positive ions (cations).
• Non-metals tend to gain electrons and
become negative ions (anions).
Example 1: Sodium and Fluorine. Draw Bohr-Rutherford diagrams of
both atoms.
+
Na
F
Electro-magnetic Force is created by the
TRANSFER of electrons forming a BOND !
Crystal Lattice Structure
• Each electron which Sodium atom lost, is
grabbed by Fluorine atom.
• There same number of Na+ and F- ions,
their ratio is 1:1, but
• ions do not form molecules. Instead, they
are tightly packed in crystals with
alternative + and – ions.
Example 2 : Aluminum and Chlorine. Draw Lewis
diagrams of both atoms
Cl
Al
Cl
Cl
Chemical Formula
• Ex 1: One Sodium for One Fluorine
– NaF
• Ex2 : One Aluminum for Three Chlorine
– NaCl3
• Subscript 3 in the formula indicates that it takes 3 Cl
atoms to 1 Al atom.
• With the right subscript, the overall charge of the
compound is zero.
Naming Ionic Bonds from
Formula
1) Write name of metal
2) Write name of non-metal
3) Non-metal suffix = IDE
NaCl
sodium
sodium
chloride
chlorine
Cations and Anions
Common Simple Cations and Anions
Cation
H 1+
Li 1+
Na 1+
K 1+
Cs 1+
Be 2+
Mg 2+
Al 3+
Ag 1+
Name
hydrogen
lithium
sodium
potassium
cesium
beryllium
magnesium
aluminum
silver
Anion
H 1F 1Cl 1Br 1I 1O 2S 2-
Name*
hydride
fluoride
chloride
bromide
iodide
oxide
sulfide
*The root is given in color.
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 86
Writing Chemical Formulas
for Ionic Compounds.
Points to note:
The metal ion/cation is always first
The nonmetal ion/anion is always written second
Steps:
1. Write the chemical symbols for each element (metal first)
2. Write the ionic charge above each element
3. Criss-cross the NUMBERS (not the signs) and write them
as subscripts
Formula from Name: Criss-Cross Rule
Example: Aluminum Chloride
Step 1:
Aluminum
Chloride
write out name with space
Step 2:
Al
3+
Cl
1-
write symbols & charge of elements
Step 3:
Al 1
Cl 3
criss-cross charges as subsrcipts
Step 4:
combine as formula unit
(“1” is never shown)
AlCl3
Criss-Cross Rule
Example: Aluminum Oxide
Step 1:
Aluminum
Oxide
write out name with space
Step 2:
Al
3+
O
2-
write symbols & charge of elements
Step 3:
Al2
O3
criss-cross charges as subsrcipts
Step 4:
combine as formula unit
Al2 O3
Criss-Cross Rule
Example: Magnesium Oxide
Step 1:
Step 2:
Step 3:
Magnesium
Mg
Oxide
2+
O
Mg 2
O2
Step 4:
Mg2O2
Step 5:
MgO
(reduce subscripts to lowest ratio)
2-
Ex. 1 Magnesium and Chlorine
Total Charge Check:
Ex.2 Calcium and Oxygen
Total Charge Check:
HINTS:
• Criss-cross rule will help you to figure
out the right subscript in the
compound formula
• Ignore subscript if it is 1
• Subscripts do not have signs: it’s a
number of ions!
• Final formula shall not indicate charge
on top
• Reduce subscripts, go by lower terms
Naming Binary Compounds
Formula
Name
BaO
barium oxide
____________________
NaBr
2 ________________
sodium bromide
1
3
MgI2
magnesium iodide
____________________
4
KCl
potassium chloride
____________________
SrF2
5 ________________
strontium fluoride
CsF
6 ________________
cesium fluoride
Multivalent Binary Compounds
Containing a Metal (Variable Oxidation Number) and Non Metal
To name these compounds (stock system):
1. Write the name of the metal
2. Followed by Roman numerals in parentheses to indicate
the oxidation number of the metal
3. Write the name of the nonmetal, with its ending replaced by
the suffix –ide.
Examples
IUPAC System
FeCl2
FeCl3
Iron (II) chloride
Iron (III) chloride
SnO
SnO2
Tin (II) oxide
Tin (IV) oxide
Common Multivalent Cations
Ion
IUPAC System
Fe 3+
Fe 2+
Cu 2+
Cu 1+
Au 3+
Au 1+
Sn 4+
Sn 2+
Pb 4+
Pb 2+
Cr 3+
Cr 2+
Ni 3+
Ni 2+
iron (III)
iron (II)
copper (II)
copper (I)
gold (III)
gold (I)
tin (IV)
tin (II)
lead (IV)
lead (II)
chromium (III)
chromium (II)
Nickel (III)
Nickel (II)
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 90
Naming Binary Compounds
Formula
Name
1
SnF4
tin (IV) fluoride
____________________
2
HgO
mercury (II) oxide
____________________
CuF2
3 ________________
copper (II) fluoride
Cu2S
4 ________________
copper (I) sulfide
5
Cr2O3
PbO2
6 ________________
chromium (III) oxide
____________________
lead (IV) oxide