Counting Atoms & Diagramming Chemical Equations Worksheet
Part A: Directions:
1) If there is a subscript, circle it.
2) If there is a coefficient, draw a square around it.
3) Count how many atoms of each element there are.
HINT: If there is no coefficient AND no subscript right after the chemical symbol, there is 1
atom of that element.
Note: ALL examples need to have their subscripts circled and
coefficients boxed.
Example 1: O2
Example 2: CaCl2
Example 3: 3CaCl2
2 O’s (oxygen) O=2
1 Ca(calcium) Ca=1
2 Cl’s(chlorine) Cl=2
3 Ca’s(calcium)
6 Cl(chlorine)
1. P4
2. H2
3. F6
P=
H=
F=
4. CH4
5. CaBr2
6. H2O2
C=
Ca=
H=
H=
Br=
O=
7. NaOH
8. Na2SO4
9. LiNO3
Na=
=
=
O=
=
=
H=
=
=
10. 2NaOH
11. 3Na2SO4
12. 4LiNO3
Na =
=
=
O =
=
=
H=
=
=
More practice on the back!
© S. Chai 2008
Ca=3
Cl=6
Part B: Directions:
1) Diagram the following equations by:
a. circling the reactants in the equation
b. Putting a square around the products in the reaction
2) Count the # of atoms on each side and write it down.
3) Answer if the equation is balanced or not by circling yes or no.
Example 4:
Example 5:
HgO → Hg + O2
Products
CH3 + 2O2
Products
C= 1
Reactants
Hg = 1
Hg = 1
O =1
O =2
Is this equation balanced? Yes / No
Reactants
C=1
H= 3
H=4
O= 4
O=4
Is this equation balanced? Yes / No
13. P + O2 → P4O10
Products
CO2 + 2H2O
14. Mg + O2 → MgO
Reactants
Products
Reactants
P=
P=
Mg =
Mg =
O=
O=
O=
O=
Is this equation balanced? Yes / No
Is this equation balanced? Yes / No
15. 4 Fe = 3O2 → 2 Fe2O3
16. Al2O3 → Al + O2
Products
Products
Reactants
Reactants
Fe =
Fe =
Al =
Al =
O=
O=
O=
O=
Is this equation balanced? Yes / No
Is this equation balanced? Yes / No
CHALLENGE (#17)
BaCl2 + H2SO4 → BaSO4 + HCl
Products
___
Reactants
Is this equation balanced? Yes / No
© S. Chai 2008