1. Compare and contrast CO2 and O2
Do now:
Compare and contrast CO2 and O2
Use the following words:
element
compound
molecule
atom
Source: Region 4 Warm Up to Science

2. Compare and contrast CO2 and O2
Are alike in that both molecules are made of elements
CO2 is a compound because it contains more than one type of atom while O2 is an element because it is made of only one type of atom
CO2 is made of 3 atoms chemically joined together while O2 is made of 2 atoms chemically joined together
Source: Region 4 Warm Up to Science

3. How do we know if we have a chemical reaction????
Chemical Reactions
How do we know if we have a chemical reaction????

4. Signs of a chemical REACTION
Has a formula explaining what is happening.
Gives off a gas – look for bubbles!
Gives off light - Fireworks!
Gives off heat - What’s this called?
Makes a precipitate – a solid at the bottom!
Changes color
Can’t change back easily original material

5. Two Words to KNOW When talking about chemical reactions
Endothermic – gets colder
( heat goes in – enter)
Exothermic – gets hotter
( heat goes out – exit)
Have students draw a picture to remind them of endo and exo as enter and exit of heat!

6. Coefficients 2Mg + O2  2MgO Reactant Product Subscript
We use chemical equations to show what is happening with a chemical reaction
Coefficients
2Mg + O2  2MgO
Reactant Product
Subscript
Label their papers with vocabulary words

7. Chemistry Terms to Know
Reactants – chemicals on the left side that we are
mixing together
Products – chemicals that we create
Coefficient – Big number in front – tells us how many
molecules I have of a chemical.
Subscript – small number below tells us how many
atoms of just one element I have.
Yield – the arrow
Write down definitions to use later

8. Figure out the number of atoms in these formulas
Example
CaCl2
1 Ca 2 Cl
Focus on using vocabulary words
Subscript is 2 tells how many atoms of Cl there are
If there is no number present Ca that means there is one!

9. Now lets add in Coefficients
Example:
3H2O
The 3 in front says we have 3 molecules of water
So we have 6 H and 3 O
Coefficient is the number in front.
They work like math 3 times the whole thing
3 x 2 = 6 H
3 x 1 = 3 O

10. Using what you know, determine if these chemical equations are balanced or not.
A balanced equation should have the same number of chemicals on both sides.

11. Source: TAKS 8 Study Guide, pg. 64

12. NaCl CO2 H3PO4 Fill in the chart: Chemical Formula
Total # of Elements in the Formula
Total # of Atoms in the Formula
NaCl
CO2
H3PO4
Source: Region 4 Warm Up to Science

13. Is this a balanced equation?
Study the following chemical equation and then fill in the chart: 2Ag + H2S  Ag2S + H2
Products
Reactants
2 silver (Ag) atoms
1 sulfur (S) atom
2 hydrogen (H) atoms
Is this a balanced equation?
Source: Region 4 Warm Up to Science

14. Source: TAKS 8 Study Guide, pg. 65

15. Work problems to determine if they are balanced or not.