1. Notes Science Tennessee SPI Objective:
Law of Conservation of Mass
Notes
Science
Tennessee SPI Objective:
Recognize that in a chemical reaction the mass of the reactants is equal to the mass of the products.
(Law of Conservation of Mass: LOCOM)
Essential Question(s)
How do I determine the number and type of atoms on each
side of a chemical equation to confirm the LOCOM?
I Can Statement
I can count the numbers of atoms on each side of chemical reactions to confirm LOCOM.
Success Criteria
I can prove that I understand LOCOM by counting the number of atoms on each side of chemical reactions.

2. Law of Conservation of Mass Key Points About All Chemical Reactions
SPI
Law of Conservation of Mass
Notes
Science
Key Points About All Chemical Reactions
You start with reactants …you end up with products
Reactants are the "ingredients" and products are what are formed during the reaction.
No atoms are created or destroyed during chemical reactions
So no mass is
created or destroyed
This is called the
Law of
Conservation of Mass
LOCOM

3. Law of Conservation of Mass 5 key Topics You Need to Know
SPI
Law of Conservation of Mass
Notes
Science
5 key Topics You Need to Know
Chemical symbols
Chemical Formulas
Chemical Equations
Subscripts
Coefficients

4. Law of Conservation of Mass
SPI
Law of Conservation of Mass
Notes
Science
Key Topic
Chemical symbols
These are the symbols (letters) that represent the elements from the periodic table.
Each element's chemical symbol starts with one capital letter
Examples:
H is a chemical symbol (for the element hydrogen)
O is a chemical symbol (for the element oxygen)
Fe is a chemical symbol (for the element iron)
Na is a chemical symbol (for the element sodium)

5. Law of Conservation of Mass
SPI
Law of Conservation of Mass
Notes
Science
Key Topic
Chemical Formulas
chemical formulas
Chemical symbols combined together =
Example:
Put the symbols H (hydrogen) and O (oxygen) together…
…and you get the formula for water… H2O
Example:
Put the symbols Na (sodium) and Cl (chlorine) together…
…you get the formula for sodium chloride… NaCl

6. Law of Conservation of Mass
SPI
Law of Conservation of Mass
Notes
Science
Key Topic
Chemical Equations
Chemical formulas combined together =
chemical equations
Examples:
Equation: 2H2 + O H2O
Equation: 2Na + Cl NaCl

7. Law of Conservation of Mass Subscripts and Coefficients
SPI
Law of Conservation of Mass
Notes
Science
Key Topics
Subscripts and Coefficients
CO2
This small number is called a subscript.
It tells you the number of atoms (2 oxygen atoms)
If there is no subscript present = only one atom
Carbon in this example does not have a subscript.
So the capital letter C represents just one atom
2CO
This big number in front is called a coefficient.
It tells you to multiply (2 carbon & 2 oxygen atoms)

8. Law of Conservation of Mass Chemical symbols and Chemical Formulas
SPI
Law of Conservation of Mass
Notes
Science
Key Topics
Chemical symbols and Chemical Formulas
Very Important!!!
Pay close attention to the letters and numbers!
Five examples that look similar, but are very different
CO2 = one carbon atom, two oxygen atoms
CO = one carbon atom, one oxygen atom
Co = one cobalt atom
2CO = two carbon atoms, two oxygen atoms
2CO2 = two carbon atoms, four oxygen atoms

9. Law of Conservation of Mass Chemical symbols and Chemical Formulas
Quick Review
SPI
Law of Conservation of Mass
Science
Key Topics
Chemical symbols and Chemical Formulas
CO2
Is this a chemical symbol or a chemical formula?
How many total atoms does it contain?
Identify the individual atoms.
How many carbon atoms?
How many oxygen atoms?
Chemical formula
Three
Carbon and Oxygen
One
Two

10. C6H12O6 Key Topics Chemical symbols and Chemical Formulas Science
Quick Review
SPI
Law of Conservation of Mass
Science
Key Topics
Chemical symbols and Chemical Formulas
C6H12O6
Is this a chemical symbol or a chemical formula?
How many total atoms does it contain?
Identify the atoms.
How many carbon atoms?
How many hydrogen atoms?
How many oxygen atoms?
Chemical formula 24
Carbon, hydrogen, and oxygen
Six
Twelve
Six

11. 2H2 + O2 2H2O Science Chemical symbols & Chemical Formulas
Quick Review
SPI
Law of Conservation of Mass
Science
Chemical symbols & Chemical Formulas
2H2 + O H2O
Is this a chemical formula or a chemical equation?
How many hydrogen (H) reactants?
How many hydrogen (H) products?
How many oxygen (O) reactants?
How many oxygen (O) products?
Does it demonstrate the law of conservation of mass?
chemical equation
Four
Four
Two
Two
Yes, it most certainly does! (explain why)

12. 2Fe + 3O2 FeO2 Science Chemical symbols & Chemical Formulas
Quick Review
SPI
Law of Conservation of Mass
Science
Chemical symbols & Chemical Formulas
2Fe + 3O FeO2
Is this a chemical formula or a chemical equation?
How many iron (Fe) reactants?
How many iron (Fe) products?
How many oxygen (O) reactants?
How many oxygen (O) products?
Does it demonstrate the law of conservation of mass?
chemical equation
Two
One
Six
Two
No, it does not! (What’s wrong with it?)

13. 2Na + Cl2 2NaCl Science Chemical symbols & Chemical Formulas
Quick Review
SPI
Law of Conservation of Mass
Science
Chemical symbols & Chemical Formulas
2Na + Cl NaCl
Is this a chemical formula or a chemical equation?
How many sodium (Na) reactants?
How many sodium (Na) products?
How many chlorine (Cl) reactants?
How many chlorine (Cl) products?
Does it demonstrate the law of conservation of mass?
chemical equation
Two
Two
Two
Two
Yes, it most certainly does! (explain why)