1. Chemical reactions

2. What are the rules for counting atoms?
Essential question
What are the rules for counting atoms?

3. What is a subscript?
SUBSCRIPTS indicate the number of atoms that an element has.
They are found BEHIND that element.

4. There are TWO atoms of hydrogen and only ONE atom of sulfur.
For example…
H2S
Subscript
There are TWO atoms of hydrogen and only ONE atom of sulfur.

5. Note
If there is no subscript behind an element, there is only ONE atom of that element!

6. What are Coefficients? COEFFICIENTS multiply the entire compound.
They are found at the front of the compound

7. For example
2 HF
Coefficient
Atoms of hydrogen= 2
Atoms of fluorine= 2

8. What if you have subscripts and coefficients in a compound?
You MULTIPLY the coefficients and subscripts.

9. For example
2 H2S
Coefficient
Atoms of Hydrogen= 4
Atoms of Sulfur= 2

10. How do you count atoms in Parentheses?
If elements are inside of PARENTHESES, the SUBSCRIPT behind the parentheses applies ONLY to the elements inside.

11. For example Ba(OH)2 Atoms of barium: 1 Atoms of oxygen: 2
Atoms of hydrogen: 2

12. Let’s Practice together!
1) MgCl2
Atoms of Mg:
Atoms of Cl: 1 2
2) 2Na(OH)
Atoms of Na:
Atoms of O:
Atoms of H: 2 2 2

13. On your own
K2(SO4)
Atoms of K:
Atoms of S:
Atoms of O: 2 1 4

14. With a partner Practice!
3CH3OH
Atoms of C:
Atoms of H:
Atoms of O: 3 10 1

15. Exit Ticket???
2Ca3(PO4)2
Atoms of Ca:
Atoms of P:
Atoms of O: 6 4 16

16. What is a Chemical reaction?
A process whereby one or more substances are changed into one or more products

17. These are the original substances before the reaction occurs
What are reactants?
These are the original substances before the reaction occurs

18. These are the resulting substances after the reaction has occurred
What are products?
These are the resulting substances after the reaction has occurred

19. What is the Law of Conservation of Mass?
The total mass of the reactants must be equal to the mass of the products for any chemical reaction
**This is the reason why we count atoms

20. Why do we count atoms? Mass is neither created or destroyed
The law of conservation of mass must be satisfied for all chemical equations and reactions
Mass is neither created or destroyed
The same number of atoms of each element must appear on each side of a chemical equation

21. How are chemical reactions represented?
Chemical reactions are represented with chemical equations

22. What do symbols in Chemical Equations mean?

23. How do we know a chemical reaction occurred?
Heat and light are produced
Gas produced
Color change
Precipitate (s) formed

24. How do you balance a chemical equation?
Step 1: Work in pencil!

25. How do you balance a chemical equation?
Step 2: List the elements present on the reactant side and the product side

26. How do you balance a chemical equation?
Step 3: Count the number of atoms for each element on each side

27. How do you balance a chemical equation?
Step 4: Add a COEFFICIENT ONLY to the compounds that will make the number of atoms equal on both sides

28. Important!!!
The Coefficient must ALWAYS go to the front of the compound Subscripts cannot be changed

29. Let’s try together ___N2 + ___H2  ___NH2
Balance the following
___N2 + ___H2  ___NH2
___Al + ___FeN2  ___AlN + ___Fe
___AgNO3 + ___Cu  ___Cu(NO3)2 + ___Ag

30. Snowman Challenge

31. What are the five types of Chemical reactions?
The five types are:
Synthesis
Decomposition
Single Replacement
Double Replacement
Combustion

32. What is a Synthesis reaction?
Two or more substances come together to form a new compound
General equation: A + X  AX
Ex. S + O2  SO2

33. Celebrity Synthesis reaction (Marriage)
Beyonce +Jay-Z ✚ 

34. What is a Decomposition reaction?
A single compound is broken down into simpler substances
General equation: AX  A + X
Ex. 2H2O2  2H2O + O2

35. Celebrity Decomposition (Divorce)
Mariah Carey + Nick Cannon  ✚

36. What is a Single Replacement reaction?
One element replaces another element in a compound
General equation: A + BX  AX + B
Ex. Mg + 2HCl  MgCl2 + H2

37. Celebrity Single Replacement reactions
Brad and Jennifer w/ Angelina ✚ 

38. What is a Double Replacement reaction?
Two compounds exchange elements to form two new compounds
General equation AX + BY  AY + BX
Ex. FeS + 2HCl  FeCl2 + H2S

39. Celebrity Double Replacement?

40. What is a Combustion reaction?
A hydrocarbon combines with O2 to produce CO2 and H2O
General equation: CH + O2  CO2 + H2O
Ex. C3H8 + 5O2  3CO2 + 4H2O

41. Celebrity Combustion
Chris Brown and Rihanna

42. How do we know what state of matter a compound is?
Look at your Solubility Chart!

43. What does soluble mean?
Can be dissolved

44. What does Aqueous(aq)mean?
Dissolved in water

45. What does insoluble mean?
Cannot be dissolved

46. What does precipitate mean?
A solid has been formed

47. If the products produced are (aq) + (aq), what is formed?
A solution No chemical reaction has occurred

48. If one of the products is a precipitate (s)
A chemical reaction will happen

49. What must be produced for a chemical reaction to occur?
A precipitate (a solid)

50. Solubility practice Identify the following as Solid (s) or Aqueous(aq)
NaCl
Cu(NO3)2
CaCO3
Fe2S3