1. Chemical Reactions

2. Chemical Reactions 7.1 Chemical reactions alter arrangements of atoms.
CHAPTER
NEW CHAPTER
Chemical Reactions
the BIG idea
Chemical reactions form new substances by breaking and making chemical bonds.
7.1
Chemical reactions alter arrangements of atoms.
7.2
The masses of reactants and products are equal.
7.3
Chemical reactions involve energy changes.
7.4
Life and industry depend on chemical reactions.
CHAPTER OUTLINE
CHAPTER RESOURCES

3. GOAL
To distinguish between physical and chemical changes

4. Chemical reactions alter arrangement of atoms
Atoms of one element differ from atoms of all other elements
Chemical bonds hold compounds together
Chemical bonds may be __________ or ____________.

5. Chemical reactions alter arrangements of atoms.
About chemical changes and how they occur
About three types of chemical reactions
How the rate of a chemical reaction can be changed

6. Atoms interact in chemical reactions.
Physical Changes
A change in state of a substance
Same substance
Substance may have different properties
Draw a picture?

7. Atoms interact in chemical reactions.
Cause chemical changes
Make new substances
Draw a picture ?

8. Four Square Vocabulary
Chemical reaction
Definition
Characteristics
Example
Nonexample

9. Four Square Vocabulary
Chemical reaction
Definition
The process by which chemical changes occur.
Characteristics
Atoms are rearranged
Produces a new substance
Bonds are broken
New bonds form between different atoms
Rust form on iron
Wood burns to form smoke and ash
Example
Liquid water changes to water vapor during boiling
Physical change
Non-example

10. Chemical Changes
Changing the substance into a new one by changing atoms
Bonds are broken
New bonds are formed

11. Atoms interact in chemical reactions.
What kind of change occurs when a substance changes state?
Physical change
Chemical change

12. EXPLORE: Chemical Changes
How can you identify a chemical change?

13. EXPLORE: Chemical Changes
What did you see on the nail?
Copper
Where do you think it came from?
The copper came from the pennies.
Did a new substance form?
Yes
What evidence supports your conclusion?
A color change

14. Evidence of Chemical Reactions
Chemical Indicators
Temperature Change
2. Formation of a Gas
Burning
(Foaming/Fizzing/ Bubbling)

15. Evidence of Chemical Reactions
Odor change
4. Corroding Acids
5. Formation of a Precipitate

16. Four Square Vocabulary
Precipitate
A solid substance that forms as a result of a reaction between chemicals in two liquids
Definition
Different physical state from the reactants
Characteristics
Solid
Seashells – formed when sea creature releases a liquid that reacts with seawater
Example
Non-example
Liquid
Gas

17. Evidence of Chemical Reactions
6. Color Change
Rusting metal
(iron + oxygen = rust)
Explosions (fireworks)
Verdigris- greened statutes
(copper + sulfur)

18. Evidence of Chemical Reactions
Cooking & some food production (cake baking, cheese production)
8. Chemical processes in nature (photosynthesis)

19. Evidence of Chemical Reactions
9. Irreversible
(New Substance is formed)

20. Evidence of Chemical Reactions
Changing Steel Wool
List the evidence/indicators of a chemical reaction.

21. Changing Steel Wool Color change Formation of a gas Temperature change
Irreversible
New Substance

22. Any type of burning

23. Rusting Metal = iron + oxygen

24. Verdigris: copper + sulfur

25. Fireworks

26. Leaves changing color

27. Plant photosynthesis

28. Cheese production

29. Soured milk

30. Eggs rotting

31. Baking a cake

32. Mixing liquids: colors change

33. Foaming (gas formation)
Ex: antacid in water

34. Corrosion due to acids
(bubbling or fizzing)

35. P. Physical Change or C. Chemical Change?
Painting a statue
Chopping wood
Crushing sugar crystals
Dissolving salt
Boiling water
Exploding firecrackers
Mixing baking soda & vinegar

36. P. Physical Change or C. Chemical Change?
Rotting eggs
Crumpling wax paper
Slicing cucumber
Fizzing antacid in water
Lighting a match
Zipping a coat up
Rusting bike chains

37. Reactants and Products
CH4 + O2 →
Reactants
Substances present at the beginning of a chemical reaction
Methane + Oxygen
Left side of the chemical equation

38. Reactants and Products
Substance(s) formed by a chemical reaction
Carbon dioxide + water
Right side of the chemical equation
→CO2 + H2O

39. Four Square Vocabulary
Reactant
A substance that is present at the beginning of a chemical reaction
Definition
Changed into a new substance
Characteristics
CH4 + O2
CO2 + H2O

40. Four Square Vocabulary
Product
A substance formed by a chemical reaction.
Definition
New bonds formed from the reactants
Rearrangement of atoms
Characteristics
Example
CO2 + H2O
Non-Example
CH4 + O2

41. Reactants and Products
What products are formed when water is broken down during a chemical change?
A. hydrogen and carbon
B. hydrogen and oxygen
C. oxygen and oxygen
D. hydrogen and hydrogen

42. Rates of Chemical Reactions
Particles collide
Occur at different rates
Concentration
Surface Area
Temperature
Catalysts
Inhibitor
Draw a picture?
Quick reaction for the match to light up
Takes months for the nail to rust

43. Rates of Chemical Reactions
Concentration
Measures the number of particles present in a certain volume.
INCREASES the rate of chemical reaction
Which atoms have a higher concentration?

44. Rates of Chemical Reactions
Surface area
Breaking a large piece of material into smaller parts
More surfaces are exposed
Amount of material does not change
INCREASES the rate of chemical reaction

45. Rates of Chemical Reactions
Temperature
Making particles move faster
More collisions/greater force
Add energy to the reactant
INCREASES the rate of chemical reaction

46. Rates of Chemical Reactions
Catalysts
A substance added
Not consumed
Can be organic, synthetic or metal
INCREASES the rate of reaction