1. Homeroom Warm Up 10/15/18
Write 1 paragraph to summarize how you spent your fall break?

2. Intervention Warm Up 10/15/18
Write 1 paragraph to summarize how you spent your fall break?

3. Science Warm Up 10/15/18
Which of these statements describes a chemical property of an object?
A. The object is white in color.
B. The object has a powdery texture.
C. The object’s density is 2.11 g/cm3
D. The object reacts with acid to form water.

4. Take a look at the picture below and complete the following sentences with your own responses
1. This makes me think of…. 2. I wonder…. 3. I have some questions…. 4. This makes me want to….

5. Introduction to Chemical Reactions
7.PS1.4 Analyze and interpret chemical reactions
to determine if the total number of atoms in the
reactants and products support the Law of
Conservation of Mass.

6. Objective
I can complete a graphic organizer to identify signs that a chemical reaction has taken place.

7. Vocabulary Terms
1. chemical reaction 2. chemical formula 3. exothermic reaction 4. chemical equation 5. endothermic reaction 6. reactant 7. law of conservation of energy 8. product 9. law of conservation of mass

8. Main Ideas Chemical Reactions are represented by Chemical Equations.
Chemical Equations are balanced to show the same number of atoms of each element on each side.
The Law of Conservation of Mass says that atoms won’t be created or destroyed in a chemical reaction. That is why you have to balance chemical equations!

9. Observing chemical Reactions
Everything around us is made of atoms. These atoms are constantly interacting with each other.
We call those interactions chemical reactions, and they are happening EVERYWHERE.
(c) 2012-Present Real Ms. Frizzle

10. Chemical Reactions are Everywhere
Cooking
Respiration

11. Chemical Reactions are Everywhere
Hair Dye
Auto Fuel

12. How do you know when a chemical reaction takes place?
Color Change
Precipitate Formation

13. How do you know when a chemical reaction takes place?
Gas Formation
Odor

14. How do you know when a chemical reaction takes place?
Temperature Change
Change in Acidity

15. Observing chemical Reactions
Changes in Energy:
Some reactions ABSORB energy
Other reactions RELEASE energy
You can usually tell if something is absorbing or releasing energy because there is a CHANGE IN TEMPERATURE.
(c) 2012-Present Real Ms. Frizzle

16. Observing chemical Reactions
Changes in Energy:
Reactions that ABSORB energy are called ENDOTHERMIC
Reaction that RELEASE energy are called EXOTHERMIC
Video
(c) 2012-Present Real Ms. Frizzle

17. Representing Chemical Reactions
Chemists observe chemical reactions and have come up with a way to represent or model what is happening by using a Chemical Equation.
Making NaCl
Solid Sodium combines with Chlorine gas to make solid Sodium Chloride:
2Na (s) + Cl2 (g)  2NaCl

18. Chemical Equations are different from Numerical Equations
Numerical Equation: 3x + 2y = 47
Chemical Equation 2Na + Cl2  2NaCl
Reactant A + Reactant B  Product
The reactants are used up in forming the product
The arrow  shows the direction of the reaction

19. Symbols used in Chemical Equations
Purpose +
Separates more than one reactant or product 
Separates reactants from products. Indicates direction of reaction
(s)
Identifies a solid state
(aq)
Identifies that something is dissolved in water
(l)
Identifies liquid state
(g)
Identifies gaseous state

20. Law of Conservation of Mass
In a chemical reaction, matter is neither created nor destroyed.
Atoms won’t change their identity (e.g. a Carbon atom can’t become an Iron atom)
This means that you have to have the same number of each type of atom on each side of the chemical equation.
Conservation of Mass Video

21. Science Closure 10/15/18
Which of the following occurrences indicates that a chemical reaction has taken place? A. An odor is produced by burning a sugar cube. B. A puddle is produced by melting an ice cube. C. A loud noise is produced by crushing a can. D. A piece of glass is produced by breaking a bottle.

22. How would you balance this equation?
Balancing Equations
After you write a chemical equation you have to balance it to make sure that the same number of atoms of each element are on each side.
How would you balance this equation?
Li + H2O  H2 + LiOH

23. Steps to Balancing a Chemical Equation
6. Check your work
5. Write the Coefficients in their lowest possible ratio
4. Change to Coefficients to make the number of atoms of each element equal on both sides of arrow
2Li(s) + 2 H2O  H2(g) + 2LiOH(aq)
3. Count the atoms of the elements in the products
1 atom Li, 3 atoms H, 1 atom O
2. Count the atoms of the elements in the reactants
1 atom Li, 2 atoms H, 1 atom O
1. Write the Skeleton Equation
Li(s) + H2O(l)  H2 (g) + LiOH (aq)

24. Another Example 7 ≠ 6! CH4 (methane gas) + O2  CO2 + H2O
Where did our atoms go?
Reactants
Products
# of Carbons = 1
# of Hydrogens = 4
# of Hydrogens = 2
# of Oxygens = 2
# of Oxygens = 3
Total atoms = 7
Total atoms = 6

25. Example Continued
Change the Coefficients to make the number of atoms of each element equal
Balance the Hydrogens:
CH4 + O2  CO H2O
Balance the Oxygens:
CH O2  CO H2O

26. Example Continued CH4 + 2 O2  CO2 + 2 H2O
Are your coefficients in their simplest ratio?
Count your atoms again to check your work:
Reactants
Products
# of Carbons = 1
# of Hydrogens = 4
# of Oxygens = 4
Total atoms = 9

27. Think – Pair - Share Try These! C2H6 + O2  CO2 + H2O
Fe2O3 + H2SO4  Fe2(SO4)3 + H2O
Hint : balance the polyatomic ion first!
CaCl2 + AgNO3  AgCl + Ca(NO3)2
Think – Pair - Share

28. Review Matter is not destroyed or created
Atoms are rearranged in chemical reactions
Chemical equations represent chemical reactions
You have to have the same number of each type of atom on the left and right hand side of a chemical equation

29. WARNING!
Don’t mess with the insides of polyatomic ions – put a square around them, or label them as X – treat the WHOLE polyatomic ion as though it were an element!
Don’t ever play around with subscripts (those little numbers that tell you how many atoms are in a molecule) e.g. C6H22O11