The subscript next to an atom indicates…
Counting Atoms
Name
period
Subscripts


Are to the right of an element symbol and below.
CO2 subscript the 2 only goes with oxygen
Coefficients

The subscript next to a parenthesis indicates…



Are whole numbers to the left of the chemical formula.
Coefficients tell how many molecules or compounds.
If it says 6H2O, it indicates that there are 6 molecules of
water. So the told # of atoms in 6 molecules of H2O ____
When there is a parenthesis around part of the compound,
treat the elements inside as one unit.
Directions for each problem
1. write down the different elements in each compound
2. write down how many of that particular atom there are
The coefficient indicates…
3. how many atoms are there total in the compound
4
1
CaB
coefficient? ___
# atoms
coefficient? ___
Al2(SO3)3
coefficient? ___
Al __ x __
# atoms
NH4Cl
coefficient? ___
parenthesis
S __ x __ x __
Ca __ x __
Li __ x __
B __ x __
O __ x __
Total # of atoms_____
HNO3
4LiO
coefficient? ___
O __ x __x __
Total # of atoms_____
Total # of atoms_____
2NaOH
coefficient? ___
2NaC2H3O2
7LiSO4
coefficient? ___
3Al2O3
coefficient? ___ 4CdSO4
coefficient? ___
# atoms
H __ x __
N __ x __
3 __ x __
Total # of atoms_____
Mg(OH)2
coefficient? ___
Mg __ x __
coefficient? ___
6C6H12O6
coefficient? ___
parenthesis
H __ x __ x __
O __ x __x __
Total # of atoms_____
2SrI2
coefficient? ___
3H2O
coefficient? ___
2(NH4)3PO4
coefficient? ___ 22K2S
coefficient? ___
parenthesis
N __ x __ x __
H __ x __ x __
P __ x __
O __ x __
Total # of atoms
2
3