Download Writing Chemical Formulas - Owen

Writing Chemical Formulas
Step #1
Write the symbol of each element, or ion
found in the compound. Include its
oxidation number.
Example:
The compound that results from the mixing of zinc and
chlorine.
Zn+2 ClExample:
The compound that results from the mixing of barium and
oxygen.
Ba+2 O-2
Step #2
You want the positive side of the
compound to balance the negative side of
the compound. You can do this by
crisscrossing the numbers, making
superscripts into subscripts, and
dropping the charge signs.
Example:
Zn+2 Cl-1
result =
Zn1Cl2
Step #3
It is not necessary to write the
subscript 1. It is understood to exist
in the absence of any other subscript.
Example:
result =
ZnCl2
Step #4
Subscripts are written in least-common
denominator form.
Example:
The compound that results from the mixing of barium and
oxygen.
Ba2 O2
becomes =
BaO
Step #5
Be sure to keep parentheses around polyatomic ions
when subscripts outside the parentheses are greater
than 1.
Example:
The compound that results from the mixing of calcium and the
polyatomic ion nitrate.
step #1:
Ca+2 (NO3)-1
step #2:
Ca1 (NO3)2
step #3:
step #4:
Ca(NO3)2
subscripts are already in least common denominator form
step #5 =
Ca(NO3)2
Step #5 (continued)
It is okay to drop parentheses around polyatomic ions
when the subscript outside the parentheses equals 1.
Example:
The compound that results from the mixing of sodium and the
polyatomic ion nitrate.
step #1:
step #2:
Na+1 (NO3)-1
Na1 (NO3)1
step #3:
step #4:
Na(NO3)
subscripts are already in least common denominator form
step #5 =
Na(NO3)