1. Counting Atoms and Balancing Chemical Equations

2. Elements, Compounds, Mixtures
Hydrogen is an element.
Oxygen is an element.
When hydrogen and oxygen bond they make the compound water.
When salt and water are combined, a mixture is created. Compounds in mixtures retain their individual properties.
The ocean is a mixture.

3. Elements, compounds, and mixtures
Elements are pure substances. When the subatomic particles of an element are separated from its atom, it no longer retains the properties of that element.
Mixtures can be separated by physical means.
Compounds can only be separated by chemical means.

4. Identifying Compounds
Each new element is identified by a capital letter
Example: H2SO4
The elements in Sulfuric Acid
Hydrogen
Sulfur
Oxygen

5. Subscripts
C12H22O11
There are 12 atoms of Carbon
There are 22 atoms of Hydrogen
There are 11 atoms of Oxygen
If there is not a subscript listed, it is understood to be 1.
Example: NaCl
There is one atom of Sodium
There is one atom of Chlorine

6. NaHCO3 HCl You Practice! Hydrogen – 1 Chlorine - 1 Sodium – 1
Carbon – 1
Oxygen -3
HCl
Hydrogen – 1
Chlorine - 1

7. There are times you will see a compound with parenthesis.
Pb(NO3)2
The 2 after the parenthesis indicates there are two sets of the parenthesis.
Pb(NO3) (NO3)
So, in counting the atoms, you would have the following:
Lead – 1 Oxygen - 6
Nitrogen -2

8. (NH4)3PO4 Mg(OH)2 You Practice!! Nitrogen – 3 Magnesium – 1
Hydrogen – 12
Phosphorus – 1
Oxygen – 4
Mg(OH)2
Magnesium – 1
Oxygen – 2
Hydrogen – 2

9. Coefficient
2H2SO4
This means there are 2 compounds of Sulfuric Acid. Think:
H2SO4 H2SO4
Counting the atoms:
Hydrogen – 4
Sulfur – 2
Oxygen - 8

10. 3H3PO4 2H2O You Practice!! Hydrogen – 9 Hydrogen – 4 Phosphorus – 3
Oxygen - 12
2H2O
Hydrogen – 4
Oxygen - 2

11. Got It????

12. Movin' On!!

13. Chemical Equations
Chemical equations express what is happening in a chemical reaction using symbols.
2K + Cl KCl
Reactant Product
yields

14. Law of Conservation of Mass
In a chemical reaction, matter cannot be created or destroyed. It can only be changed.
Therefore the Reactants must equal the Products for the equation to be balanced

15. What does that mean??
The reactants MUST contain the same elements and the same number of each element as the product. BUT they CAN be in different compounds.

16. HUH????? H2 + O2 H2O Reactants Products H = 2 H = 2 O = 2 O = 1
This cannot happen. An oxygen atom cannot be destroyed.

17. So what do we do?
The chemical equation must be written according to the law.
AGAIN --- HUH???
H2 + O H2O is the production of water. Well, how it actually happens in nature is this….
2H2 + O H2O
Reactants: Products:
H = H = 4
O = 2 O = 2

18. Do I Need to Know How to Balance?
NOT YET. You need to be able to recognize if the chemical reaction follows the law of conservation of mass.
Na + O Na2O
Mg + 2HCl MgCl2 + H2
NOPE
YUP!!

19. You Practice!!! NOPE YUP YUP HgO Hg + O2 Hg = Hg = O = O =
N2 + 3H2 2NH3
Zn + 2HCl ZnCl2 + H2
NOPE
YUP
YUP

20. More Practice NOPE NOPE YUP K + Br2 2KBr 2Fe + O2 6Fe2O3
2Na + 2H2O 2NaOH + H2
NOPE
NOPE
YUP

21. Got It???

22. Balancing Chemical Equations
H2 + O H2O
Reactants: H = 2 Products: H = 2
O = O = 1
What do we multiply by 1 to get 2?

23. Keep Going…. H2 + O2 2H2O Reactants: H = 2 Products: H = 4 O = 2 O = 2
Now the Oxygen is balanced but Hydrogen is not, so what do we multiply by 2 to get 4?

24. Almost There!!! 2H2 + O2 2H2O Reactants: H = 4 Products: H = 4
O = O = 2
Now it is balanced!!! Congratulations, you have now learned the hardest thing we will do all year!!

25. Now You Practice ___HgO ___Hg + ___O2 ___K + ___Br2 ___KBr Hg = Hg =
O = O =
___K + ___Br ___KBr
K = K =
Br = Br =

26. Last Couple… ___N2 + ___H2  ___NH3 C = C= H = H = O = O = N = N =
___C2H6 + ___O2  ___CO2 +___H2O
C = C=
H = H =
O = O =

27. Warm Up 3/11 Write Q&A
Why do we have to balance equations? (What law do we have to follow?)

28. Warm Up 3/10 Write Q&A Balance the Following:
HNO3 + Ca(OH)2  Ca(NO3)2 + H2O

29. Warm Up 3/8 Write the Following:
The Law of Conservation of Mass
In a chemical reaction, matter cannot be created or destroyed. It can only be changed.

30. Warm Up 3/5 Write Q&A
How many atoms are in 3Pb(OH)4? Pb O H

31. Warm Up March 4 Write Q&A
The vertical columns on the periodic table are called ______________ and they correspond to the number of __________
The horizontal rows on the periodic table are called ____________ and they correspond to the number of __________

32. Warm Up 3/9 Is it balanced? Show your work!!
Al O > Al2O3
SiCl H2O ---> H4SiO HCl

33. What are you learning today?
Monday, October 18
Go Rangers!!
Students will be able to: practice counting atoms
Go over Counting Atoms Worksheet
Chemical Formula Practice Worksheet (in class)
Grade (if time)
Objective:
What are you learning today?
Warm Up
How many atoms are in Pb(OH)4? Pb O H
Take out a grading pen and Counting Atoms WS
Clear everything else off your desk
Things to do:

34. What are you learning today?
Monday, October 18
Go Rangers!!
Students will be able to: practice counting atoms
Go over Counting Atoms Worksheet
Chemical Formula Practice Worksheet (in class)
Grade (if time)
Objective:
What are you learning today?
Warm Up
How many atoms are in Pb(OH)4? Pb O H
Take out a grading pen and Counting Atoms WS
Clear everything else off your desk
Things to do:

35. What are you learning today?
Thursday, October 21
Go Rangers!!
pap
Objective:
What are you learning today?
Students will be able to: Review the differences between Physical and Chemical Changes
Go Over #1-5
Balancing Equations Activity
Do #1-7 for HW
5H2
What number represents the Coefficient? ____
What number represents the Subscript? _____
What element is represented by the letter "H"? ___________
How many "H's" do you have? _____
Warm Up
Things to do:
Take out Worksheet from Yesterday #1-5

36. What are you learning today?
Wednesday, October 20
Go Rangers!!
pap
Objective:
What are you learning today?
Students will be able to: use the Law of Conservation of mass to Balance Equations
Grade #11-20
Balancing Equations Activity
Do #1-7 for HW
Balance the Following:
__HNO3 +__Ca(OH)2  __Ca(NO3)2 + __H2O
Warm Up
Things to do:
Take out a grading pen
Clear everything else off your desk

37. What are you learning today?
Wednesday, October 20
Go Rangers!!
Objective:
What are you learning today?
Students will be able to: use the Law of Conservation of mass to Balance Equations
Go over Homework #1-10
Notes on Balancing Equations
Balancing Equations Worksheet #1-5
Do #11-20 on your Homework from yesterday
What law do we have to follow when we are figuring if equations are balanced or not? Why?
Warm Up
Things to do:
Take out your homework from yesterday

38. What are you learning today?
Tuesday, October 19
Go Rangers!!
Objective:
What are you learning today?
Students will be able to: use the skill of counting atoms to tell if an equation is balanced
Notes on Balancing Equations
Balancing Equations Worksheet #1-10
How many atoms are in 3Pb(OH)4?
(look at what you did yesterday!!) Pb O H
Warm Up
Things to do:
Take out a grading pen
Clear everything else off your desk