Keeping Track of Atoms
12/12/16
Directions: Keeping Track of Atoms
1.
2.
3.
4.
Read through this Power Point.
Write down (into your notes) any key vocabulary and or concepts.
Complete the front and back of this worksheet.
Create your own lines like questions 3 a, b and 4 a, b. and fill the
lines in with the correct numbers of each atom on the reactants
and products of the equation.
To get credit, you must show your work!
Don’t forget to decide if it is balanced or not!
Worksheet: Keeping Track of Atoms
Key Vocabulary:
• Subscript:
• the small number after that element that designates the number of atoms.
• Coefficient:
• the large number in front of the molecule that designates the number of
molecules in the reaction.
• Example:
CaCO3
Subscript
4Mg(OH)2
Coefficient
Worksheet: Keeping Track of Atoms
• The law of conservation of mass and energy.
• Nothing is created or destroyed.
• It can be transferred and/or rearranged.
• A chemical equation is balanced if there are the same
number of each kind of atom on both sides of the equation.
Worksheet: Keeping Track of Atoms
• CaCO3
Ca = 1 (1 atom of Ca per molecule).
C = 1 (1 atom of C per molecule)
O = 3 (the subscript is 3, this means there are 3 oxygen atoms per molecule).
• 3H2
H = 6 (2 atoms of hydrogen per molecule AND 3 molecules of H 2)
• 4Mg(OH)2
Mg: 1 atom of Mg per molecule = 4 total Mg (4 molecules x 1 Mg atom)
O: 2 atoms of O per molecule = 8 total O (4 molecules x 2 O atoms/molecule)
H: 2 atoms of H per molecule = 8 total H (4 molecules x 2 H atoms/molecule)
(OH)2
= 2 oxygen atoms and 2 Hydrogen atoms
Distributive property (1 atom of O in each OH = 2 oxygen atoms total)
Don’t forget to complete the other problems for question 2!
Worksheet: Keeping Track of Atoms
Key Vocabulary:
• Reactant- the substances that are reacting together to form a
product
• Found on the Left Side of the equation.
• Multiple reactants are separated by a + sign
• An arrow comes after the reactants and before the products
• Products- the substances that are created through the
rearrangement of atoms from the reactants.
• Found on the Right Side of the equation.
• Multiple products are separated by a – sign.
• The products follow the arrow.
Worksheet: Keeping Track of Atoms
2 Na + 2 H2O  2NaOH + H2
Reactants
Remember (2x2= 4)
Remember (2x1= 2)
Products
2 :Na Na: 2
4 :H H: 4
2 :O O: 2
Step 1: Count the number of each atom on the Reactant Side of the equation.
Step 2: Count the number of each atom on the Product Side of the equation.
Step 3: Look to see if each of the atoms have the same number on the reactants and products.
This is a balanced chemical equation because there are 2 atoms of Na on each side AND four
atoms of H on each side and 2 atoms of O on each side.
Worksheet: Keeping Track of Atoms
NaCl + F2  NaF + Cl2
Reactants
Remember (2x2= 4)
Remember (2x1= 2)
Products
1 :Na Na: 1
1 :Cl Cl: 2
2 :F F: 1
Step 1: Count the number of each atom on the Reactant
Side of the equation.
Step 2: Count the number of each atom on the Product Side of the equation.
Step 3: Look to see if each of the atoms have the same number on the reactants and products.
This is NOT a balanced chemical equation because both Chlorine and Fluorine do not have
same amount of atoms on each side of the equation.
Directions: Keeping Track of Atoms
1.
2.
3.
4.
Read through this Power Point.
Write down (into your notes) any key vocabulary and or concepts.
Complete the front and back of this worksheet.
Create your own lines like questions 3 a, b and 4 a, b. and fill the
lines in with the correct numbers of each atom on the reactants
and products of the equation.
To get credit, you must show your work!
Don’t forget to decide if it is balanced or not!