6.3 Naming
Compound
and Writing
Formulas
Key Concepts:
1. What information do the name and
formula of an ionic compound
provide?
2. What information do the name and
formula of a molecular compound
provide?
I. Naming Binary Ionic Compounds
A. Compound made from
only two elements
B. Name of the cation
first, then the name
of the anion.
C. Name of the anion
ends in the suffix “ide.”
See Table 16 on p. 171
I. Naming Binary Ionic Compounds
D. Examples- Name the following
MgBr2
________________________________
Al2S3
______________________________
CaCl2
______________________________
AlCl3
______________________________
II. Naming Binary Compounds with
Metals with Multiple Ions
A. Many transition metals that
form more than one type
of ion.
B. Show the charge of the
cation when naming the
compound.
C. Use Roman numerals in
D. See Table 17 on p. 172 or
parenthesis to show the
periodic table in your planner
charge of the cation.
II. Naming Binary Compounds with
Metals with Multiple Ions
E. Examples- Name the following:
Cu2O
________________________________
FeF3
________________________________
Mn2O7
________________________________
NiBr3
________________________________
III. Naming Binary Compounds with
Polyatomic Ions
A. Covalently bonded group of
ions that has a positive or
negative charge and acts
like a unit.
B. Most polyatomic ions are
anions.
C. May need to use parenthesis
to show how many of each D. See the Table 19 on page 173polyatomic unit is in the
Tape the hand out into
compound.
your planner.
III. Naming Binary Compounds with
Polyatomic Ions
E. Examples- Name the following:
Na2CO3
________________________________
Be (OH)2
________________________________
KClO3
________________________________
NH4OH
________________________________
IV. Writing Formulas for
Ionic Compounds
A. Overall charge must equal zero.
B. To write the chemical formula for an ionic compound:
1. Write the element symbol of the cation first, then anion.
2. Write the charge with the number first then the sign.
*Write the formula for lithium oxide
Li1+
O2-
IV. Writing Formulas for
Ionic Compounds
3. Use subscripts to indicate the number of ions needed to balance
the charges.
4. Use the crisscross method to determine correct subscripts.
http://ths.talawanda.org/~bramblen/classroom/Pictures/criss-cross%20method.JPG
IV. Writing Formulas for
Ionic Compounds
5. Examples:
a. Write the formula for aluminum nitride.
Step 1: Need the symbol & charge for
each element in the compound.
Step 2: Write each ion beside each other.
IV. Writing Formulas for
Ionic Compounds
Step 3: Crisscross the value (not the sign) of the subscripts.
*Check – does the overall charge = 0?
Step 4: Rewrite the formula without superscripts.
If both subscripts are the same, simplify to 1:1 ratio)
IV. Writing Formulas for
Ionic Compounds
b. Write the chemical formula for rubidium iodide.
IV. Writing Formulas for
Ionic Compounds
c. Write the chemical formula for barium fluoride.
IV. Writing Formulas for
Ionic Compounds
d. Write the chemical formula for tin (IV) oxide.
IV. Writing Formulas for
Ionic Compounds
e. Write the chemical formula for cobalt (II) bromide.
IV. Writing Formulas for
Ionic Compounds
f. Write the chemical formula for calcium phosphate.
IV. Writing Formulas for
Ionic Compounds
g. Write the chemical formula for ammonium sulfate.
V. Molecular Compounds
A. Most metallic element appears first in the
name.
1. Farther to left on the periodic table
2. Closer to the bottom, if both are in the same
group.
B. Rules for naming:
1. Use prefixes that tell how many of each
atom are in the compound.
See Table 20 p. 175 (must know!!)
2. Use suffix “-ide” for the name of the second
element.
http://ths.talawanda.org/~bramblen/classroom/Pictures/prefixes.JPG
V. Molecular Compounds
C. Name the following:
CCl4
________________________________
SO2
________________________________
P4S5
________________________________
AsF5
________________________________
N4O
________________________________
V. Molecular Compounds
D. Write the formula for the following:
Chlorine trifluoride
______________________
Beryllium dichloride
______________________
Iodine pentafluoride
______________________
Diphosphorus pentoxide
______________________