Counting Atoms & Balancing Equations Worksheet

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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 |3 Ca’s(calcium) Ca=3 |

| |2 Cl’s(chlorine) Cl=2 |6 Cl(chlorine) Cl=6 |

|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!

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 |CH3 + 2O2 CO2 + 2H2O |

|Products Reactants |Products Reactants |

|Hg = 1 Hg = 1 |C= 1 C=1 |

|O =1 O =2 |H= 3 H=4 |

|Is this equation balanced? Yes / No |O= 4 O=4 |

| |Is this equation balanced? Yes / No |

| | |

|P + O2 → P4O10 |Mg + O2 → MgO |

|Products Reactants |Products Reactants |

|P = P = |Mg = Mg = |

|O = O = |O = O = |

|Is this equation balanced? Yes / No |Is this equation balanced? Yes / No |

| | |

|4 Fe = 3O2 → 2 Fe2O3 |Al2O3 → Al + O2 |

|Products Reactants |Products 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 |

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