1. Elements, Compounds, and Chemical Reactions
8th Grade Science

2. DO NOW Wednesday October 25th
Copy the following:
NEW POLICY
A timer will be set on the DO NOW. When time is up, work will be checked.
If DO NOW is not complete, you will get a mark on clip board.
If you don’t know how to do the DO NOW, you should at least write the question.
3 marks on clip board, choice card signed for off-task behavior.
5 marks on clip board, parents will be called.
7 marks on clipboard, write-up sent to office.
Marks on clip board will be given for ANY off-task behavior during class.
Timer

3. TODAY’S DO TODAY’S PLAN Create a diagram of a Lewis Dot Structure
Differentiate between an element and a compound
Distinguish between a symbol and a formula
TODAY’S DO
Quiz: Calculating protons, neutrons, and electrons, drawing electronic structures
Draw Lewis Dot Structures for elements
Differentiate between elements, compounds, and mixtures

4. Lewis Dot Structures
Use dots to represent the number of valence electrons (outermost electrons) in an atom
Look at the group number (column number)
That is the number of dots that will be around the symbol for the element
Maximum = 8 valence electrons = 8 dots
Example:
Nitrogen = Group 5 = 5 valence electrons = 5 dots

5. DO NOW Thursday October 27th
Timer
How many valence electrons does Tin (Sn) have? Draw its Lewis Dot Structure.

6. TODAY’S DO TODAY’S PLAN
Differentiate between an element and a compound
Distinguish between a symbol and a formula
Describe and give examples of physical and chemical properties.
Compare and contrast physical and chemical changes.
TODAY’S DO
Differentiate between elements, compounds, and mixtures
Review physical and chemical properties.
Differentiate between physical and chemical changes.

7. Element Made of only one type of atom Represented by a symbol
1 capital letter Ex. C
1 capital and one lower case letter Ex. Na

8. Compound
Made of 2 or more elements chemically combined (chemical reaction)
Consist of a new substance with different properties than the elements it was made of
Represented by a chemical formula
Will have at least 2 capital letters in the formula Ex. NaCl or CaCO3

9. Mixture
Made of 2 or more substances (elements or compounds) physically combined (NOT a chemical reaction)
May have the word “and” in the name
Two types:
1. Heterogeneous:
Appears different, can see different things in it, not evenly mixed
Example: cereal and milk, a hamburger
2. Homogeneous : also called a solution
Appears the same throughout, evenly mixed
Example: sweet tea

10. Elements, Compounds, and Mixtures

11. Which is it?? Element, Compound, Homogeneous Mixture or Heterogeneous Mixture1. 3. 2.
4. Table sugar (C6H12O6)
5. Helium gas (He)

12. Which is it?? Element, Compound, or Mixture

13. Physical and Chemical Properties and Changes

14. Properties Which type are easily observed or measured?
PHYSICAL
Give examples of physical properties.
Size, shape, color, malleable, ductile, conductor, shiny
Which type can only be observed when the identity of a substance is changed?
CHEMICAL
Give examples of chemical properties.
Corrosive, reactive, flammable, explosive, combustible, able to rust

15. Physical Change It is a physical change if . . .
A change in the appearance, without changing the identity of the material.
It is a physical change if . . .
Can be reversible, or irreversible
Substance may seem different, but the way the atoms link up is the same.
It changes shape or size
It dissolves.
Or the substance changes phase.

16. Chemical Changes
Chemical changes occur when a substance reacts and forms one or more new substances.
You know a chemical change has occurred when there is. . .
A change in color or odor.
Production of a gas. (bubbling and fizzing)
Formation of a precipitate.(solid)
Absorb or release energy (gets hot or cold).

17. Examples of Chemical Changes:
Digesting:
Color change, odor
Change, produces a
Gas, releases energy
Burning
Or Combustion:
Color change, odor change,
Produces a gas, gets hot
Rusting:
Color change
Molding:
Color change,
Odor change
Decaying:
Color change,
Odor change
Corroding:
Color change

18. What kind of change is it?
physical
Its still a ribbon, didn’t change its identity.

19. What kind of change is it?B
chemical
Its changing wood to ash, color change, odor change, gas produced, gets hot

20. What kind of change is it?
physical
Snow is frozen water, when it melts it’s still water, didn’t change identity.

21. What kind of change is it?
physical
Ice is frozen water, when it melts it’s still water, didn’t change identity.

22. What kind of change is it?
chemical
It’s producing a gas because its bubbling.

23. What kind of change is it?
physical
Even when you paint it, the wall is still a wall made of wood and drywall,
didn’t change identity.

24. DO NOW Friday October 28th
Timer
1. Tell if each property is physical or chemical. A. Color B. Conductivity C. Reactivity D. Solubility 2. What are the four indicators that a chemical change is happening? 3. Tell if each change is physical or chemical. A. Rusting B. Melting C. Dissolving D. Reacting with acid

25. TODAY’S DO TODAY’S PLAN
Describe and give examples of physical and chemical properties.
Compare and contrast physical and chemical changes.
TODAY’S DO
Conduct Physical and Chemical Changes Lab

26. Physical Properties Before
Copy this table.
Station
Physical Properties Before
Results
Type of Change
How do you know? 1 2 3 4 5 6 7

27. Lab Expectations Stay with your group at your table. Stay on task.
Behave appropriately.

28. DO NOW Tuesday November 1st
Timer
Classify each as an element, compound, homogeneous mixture, or heterogeneous mixture:
Vinegar (H2C2H3O2)
Pancake syrup
Chili
A copper bracelet (Cu)

29. Conclude the number of atoms of each element in a compound.
TODAY’S PLAN
Conclude the number of atoms of each element in a compound.
Explain the Law of Conservation of Matter.
TODAY’S DO
Practice counting the number of atoms of each element in a compound using the compound’s formula.
Discuss chemical equations and the Law of Conservation of Matter.

30. Counting Atoms
The chemical formula for a compound tells us the types of elements in the compound.
Subscripts in the formula also tell us the number of atoms of each element in the compound.

31. Counting Atoms Examples: CuO (copper oxide) CaCl2 (calcium chloride)
Cu = 1 atom
O = 1 atom
CaCl2 (calcium chloride)
Ca = 1 atom
Cl = 2 atoms
H2C2H3O2 (vinegar)
H = = 5 atoms
C = 2 atoms
O = 2 atoms

32. Counting Atoms
Sometimes, the formula for a compound will have a coefficient in front of it.
This coefficient should be multiplied by the subscript to determine the number of atoms of each element in the compound.
Coefficient 

33. Counting Atoms Examples: 2 CaCl2 4 NH4OH Ca = 2 x 1 = 2 atoms
Cl = 2 x 2 = 4 atoms
4 NH4OH
N = 4 x 1 = 4 atoms
H = 4 x (4 + 1) = 20 atoms
O = 1 x 4 = 4 atoms

34. Let’s Practice: Tell the number of atoms of each element in these compounds
1. SnCl KCl
2. Cu2SeO H2C2H3O2
3. AsBr3

35. Chemical Equations
try/chemicalequations/

36. Chemical Equations
Show on paper what is happening during a chemical reaction in a beaker or test tube.
(before arrow)
(after arrow)

37. Law of Conservation of Matter
During a chemical reaction, matter cannot be created or destroyed, only transformed from one form to another.
= same number and kinds of atoms/elements on each side of a chemical equation
This why we MUST balance chemical equations.

38. DO NOW Wednesday November 2nd
How many atoms of each element are in the following compounds?
H2CO3
3Na2SO4
Why do we have to balance chemical equations?

39. Explain and interpret the Law of Conservation of Matter.
TODAY’S PLAN
Explain and interpret the Law of Conservation of Matter.
Balance chemical equations.
TODAY’S DO
Discuss chemical equations and the Law of Conservation of Matter.
Balance equations.

40. Balancing Chemical Equations
We must put coefficients in front of the formulas for compounds in the equation to make the number of atoms on each side of the equation equal.

41. Balancing Equations Example
_____ Na + _____Cl2  _____ NaCl

42. Balancing Equations Example
_____ Al + _____O2  _____ Al2O3

43. Balancing Equations Example

44. DO NOW Thursday November 3rd
Why do we have to balance chemical equations?
Balance the following equation. Show your work.
____NaBr + ____Cl2  ____NaCl + ____Br2

45. Explain and interpret the Law of Conservation of Matter.
TODAY’S PLAN
Explain and interpret the Law of Conservation of Matter.
Balance chemical equations.
TODAY’S DO
Balance equations.
Exit Slip/Quiz

46. Balancing Equations Example
____S + ____O  ____SO3

47. Balancing Equations Example
____N2 + ____H  ____NH3

48. Balancing Equations Example
__HCl + __CaCO3  __CaCl2 +__H2O + ___CO2

49. DO NOW Wednesday November 9th
Why do we have to balance chemical equations?
Balance the following equation. Show your work.
__HCl + __CaCO3  __CaCl2 +__H2O + __CO2

50. Illustrate Mastery of Chemistry Learning Targets
TODAY’S PLAN
Illustrate Mastery of Chemistry Learning Targets
TODAY’S DO
Complete Chemistry Review Sheet