1. BELL WORK:
When wood burns, a small amount of ashes is made. Why is the mass of the wood before the fire not equal to the mass of the ashes after the reaction?
The mass of the wood has been destroyed.
The mass of the wood and the oxygen that allowed it to burn will equal the mass of the ashes and the gas.
The mass of the wood and the ashes equals the mass of the oxygen and the smoke given off during the time that the wood burned.
The wood has holes in it so it is actually lighter in mass than it appears. The mass of just the wood will equal the mass of just ashes after the burning.

2. Who’s Ready for TCAP?!!!! SPI 0807.9.1—True or False
Electrons are smaller than protons and neutrons.
SPI —Identify the compound.
Co He HBr Na Cl
SPI —Elements are that shiny, malleable, and ductile can be found to the __________ of the zigzag line on the periodic table.
left
SPI —In the following chemical equation, identify the reactants.
CH4 + O2 → CO2 + H2O

3. Let’s review…
1. The law of conservation of mass says that matter is never _________ or destroyed.
2. According to the law of conservation of mass, if there are 20 atoms on the reactant side, there must be ______ atoms on the product side.
3. The chemical formula for dinitrogen trioxide is written like __________.
created 20
N2O3

4. Sodium sulfate and barium chloride react with each other to form sodium chloride and barium sulfate as shown.
Which statement MOST accurately describes the mass of the reactants compared to the mass of the products?
The mass of the reactants is the same as the mass of the products.
The products have a greater mass because matter was created during the reaction.
The reactants have a greater mass because some of the mass was converted to heat.
The reactants have a greater mass because some matter was destroyed by the reaction.

5. Count those atoms!
How many sodium atoms?
2 Na2OH 4

6. Count those atoms!
How many total atoms?
Na2OH2 5

7. Count those atoms!
How many total atoms?
3 NaCl 6

8. Does the equation above represent the law of conservation of mass?1.
Reactants 2.
Products
4P + 5O3 → P4O10 3. 4.
Coefficient
Subscript
Does the equation above represent the law of conservation of mass?

9. Balancing Chemical Equations
STEP 1: Box around compounds STEP 2: Identify elements STEP 3: Count atoms STEP 4: Add Coefficients STEP 5: Update numbers

10. Balancing Chemical Equations3
AlBr K → KBr Al 3
Al = 1
Br = 3
K = 1
Al =
Br =
K =
Al = 1
Br = 1
K = 1
Al =
Br =
K = 3 3 3
STEP 1: Box around compounds
STEP 2: Identify elements
STEP 3: Count atoms
STEP 4: Add Coefficients
STEP 5: Update numbers