WRITING FORMULAS
Does the second word end with -ide?
yes
no
/
\
Is the second word
"hydroxide"?
\
no
yes
\
|
\
\
Is the first word
"ammonium"?
\
|
no
yes ----------------------------------------------> TERTIARY
COMPOUND
|
BINARY COMPOUND
Is the first word the name of a
metal or "ammonium"?
Is the first word the name of
a
/
|
nonmetal or a metal? ---------> General
Rules for Writing Formulas 1.
Write "NH4+1"
|
1. Write the symbol for the metal
with 2.
Write symbol for the second
1. Write symbol for
first
its oxidation
number. element with its oxidation
element.
2. Write the symbol for the second number
or formula for poly-
2. Prefix of first word
tells element
with its oxidation
number atomic
ion with its oxidation
subscript of first
symbol. or formula for polyatomic ion
with number
3. Write symbol for
second its oxidation
number 3.
Cross out the "+" and "-".
element.
3. Cross out the "+" and
"-".
4. Reduce (simplify) the
4. Prefix of second
word 4.
Reduce (simplify) the numbers
if
numbers if possible.
tells subscript of
second
possible. 5.
"Criss-cross" the numbers.
symbol.
5. "Criss-cross" the
numbers. (The
oxidation number of
(The oxidation number of the
first
ammonium becomes the
part becomes the subscript of
the
subscript of the second part.
second part. The oxidation
number
The oxidation number of the
of the second part becomes
the
second part becomes the
subscript of the first
part.)
subscript of the first part.)
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EXAMPLES:
1.) calcium oxide
2.) carbon tetrachloride
3.) ammonium chromate
4.) lead (II) nitrate
5.) aluminum hydroxide
6.) iron (III) bromide