Chemical Reactions

1
Chemical Reactions

• Chapters
• 5 sections 1, 2 3
• 6 sections 2, 3

2
Valence Electrons

• Only electrons involved in bonding. The number of
  valence electrons affects whether atoms bond or
  not.

3
Electron Dot Diagram or Lewis Dot Structures

• Just the symbol and the of valence electrons.

Li
Br
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6
Lewis Structures

• Find out which group (column) your element is in.
• This will tell you the number of valence
  electrons your element has.
• You will only draw the valence electrons.

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7
Groups - Review
Group 8 8 electrons
Group 1 1 electron
Except for He, it has 2 electrons
Group 2 2 electrons

• Each column is called a group

3, 4, 5, 6, 7

• Each element in a group has the same number of
  electrons in their outer orbital, also known as
  shells.

• The electrons in the outer shell are called
  valence electrons

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8
Lewis Structures

1. Write the element symbol.
2. Carbon is in the 4th group, so it has 4 valence
   electrons.
3. Starting at the right, draw 4 electrons, or dots,
   counter-clockwise around the element symbol.

C
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Lewis Structures

1. Check your work.
2. Using your periodic table, check that Carbon is
   in the 4th group.
3. You should have 4 total electrons, or dots, drawn
   in for Carbon.

C
10
Please select a Team.

1. Team 1
2. Team 2
3. Team 3
4. Team 4
5. Team 5
6. Team 6
7. Team 7
8. Team 8

11
Which dot structure is correct?

• A
• B

A
B
N
N
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Which dot structure is correct?

• A
• B

Mg
Mg
13
Which dot structure is correct?

• A
• B

Ga
Ga
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Team Scores
2.25 Team 3
2 Team 2
2 Team 4
2 Team 6
2 Team 7
1.75 Team 5
1.75 Team 8
1.6 Team 1


15
Bonding

• Chemical bonds form when a chemical reaction
  occurs. The bonds form when either valence
  electrons are transferred, taken away or shared
  between atoms.

16
Reactivity

• When bonds form the atoms become more stable.

17
Ionic Bonds

• Electron Transfer Atoms with fewer than 4
  valence electrons will transfer them to an atom
  with four or more, causing the atoms to become
  stable.
• Metal nonmetal Ionic

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Ions

• If an atoms loses an electron it becomes a
  positive Ion.
• If it gains an electron it becomes negative.

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Ions and Ionic Bonds

• Ionic bonds form as a result of the attraction
  between positive and negative ions.

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24
Covalent Bonds

• When compounds are held together by sharing
  electrons.
• Common covalent compounds are Fat, proteins,
  carbs, cotton and wool.

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Covalent Bonds cont

• They have low melting points and boiling points.
• Poor conductors of electricity.
• Two or more non-metals bonded together.

26
How Covalent Bonds Form

• The force that holds atoms together in a covalent
  bond is the attraction of each atoms nucleus for
  the shared pair of electrons.

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Ionic and Covalent Bonding

• Ionic and covalent bonding

30
Team Scores
2.25 Team 3
2 Team 2
2 Team 4
2 Team 6
2 Team 7
1.75 Team 5
1.75 Team 8
1.6 Team 1


31
Is CO2 Ionic or Covalent?

1. IONIC
2. COVALENT

32
Is NaBr Ionic or Covalent?

1. IONIC
2. COVALENT

33
Is Cl2 Ionic or Covalent?

1. Ionic
2. Covalent

34
Is K3P Ionic or Covalent?

1. Ionic
2. Covalent

35
Team Scores
6 Team 3
6 Team 7
5.75 Team 2
5.75 Team 4
5.75 Team 8
5.67 Team 6
5.4 Team 1
5.25 Team 5


36
Nonpolar Bonds

• Bonds cancel each other out ? Typically covalent
  bonds.

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Polar Compounds

• When electrons are shared unequally, it causes
  one atom to be slightly positive and the other
  will be slightly negative.

39
Electrons are pulled closer to Oxygen giving it a
slight negative charge.
Hydrogen gets a slight positive charge because
the electrons are pulled further away from
hydrogen.
40
Chemical Reactions

• Production of new materials that are chemically
  different from the beginning materials.

41
Properties and Changes in Matter

• Matter can undergo both physical change and
  chemical change.

42
Evidence for Chemical Reactions

• Color change
• Gas production
• Changes in temperature
• Changes in properties

43
Controlling Rates of Reaction

• Concentration the more particles to react, the
  faster the reaction.

44
Controlling Rates of Reaction cont

• Surface area the more particles that are exposed
  in a reaction, the faster it is.

• Temperature If temperature is increased, then
  the rate of reaction increases.

45
Controlling Rates of Reaction cont

• Catalyst Helps reaction happen by lowering
  activation energy.

• Inhibitor Decreases rate of reaction.

• Enzyme Biological catalyst in our bodies that
  allow important bodily functions to occur.

46
Temperature

• Concentration

Surface Area
47
Please select a Team.

1. Team 1
2. Team 2
3. Team 3
4. Team 4
5. Team 5
6. Team 6
7. Team 7
8. Team 8

48
If you want to increase the rate of reaction you
can

1. Decrease temperature
2. Increase surface area
3. Add an inhibitor

49
Which one below would indicate a chemical
reaction has occurred?

1. The substance freezing
2. The substance being crushed
3. The substance bubbles to produce a green gas

50
If you put Alka Seltzer in Water, it bubbles
producing Carbon Dioxide, this would be

1. Both a chemical and physical change
2. Physical change only.
3. Chemical change only

51
When Alka seltzer produces CO2, Is CO2 Ionic or
Covalent?

1. IONIC
2. COVALENT

52
Is NaCl Ionic or Covalent?

1. IONIC
2. COVALENT

53
Team Scores
5 Team 7
4.75 Team 6
4.5 Team 3
4.5 Team 4
4.33 Team 2
4.2 Team 1
3.75 Team 5
3.75 Team 8


54
Every chemical reaction involves energy in one
of two ways

• Exothermic Energy is released.
• Endothermic Energy is absorbed.

55
Endothermic Reaction
56
Activation Energy

• The minimum amount of energy needed to get a
  reaction started.

57
Chemical Equations

• A shorter, easier way of showing chemical
  reactions using symbols instead of words.
• Chemical Formula shows the ratio of elements in
  a compound
• H2O
• NaCl
• CO2

58
Structure of an Equation

• Reactants materials you start with
• Products materials you end with

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Reactant Reactant ? Product
H2 O2 ? H2O2
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Conservation of Mass

• The amount of matter in a chemical reaction does
  not change, so the total mass of the reactants
  must equal the total mass of the products.

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Conservation of Matter
63

• Law of Conservation of Mass

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Classifying Chemical Reactions

• Synthesis
• Decomposition
• Single Replacement
• Double Replacement

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Synthesis

• Two or more elements combine to form a more
  complex compound.
• A B ? AB
• Cat Fish ? Catfish
• Example C 2Cl2 ? CCl4

66
Decomposition

• Breaks down compounds into simpler substances.
• AB ? A B
• Schoolbook ? school book
• Example 2Al2O3 ? 4Al 3O2

67
Replacement

• A reaction in which one element replaces another
  in a compound, or two elements in different
  compounds trade places
• AB C ? AC B (Single)
• AB CD ? AC BD (Double)
• T.V. screen door knob ? T.V. knob screen door
• HCl NaOH ? H2O NaCl

68

• Types of Reactions

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Synthesis or Decomposition? H20? H2 O2

1. Synthesis
2. Decomposition

70
What are the reactants?Fe O2 ? FeO2

1. FeO2
2. Fe O2

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Synthesis or Decomposition? Fe O2 ? FeO2

1. Synthesis
2. Decomposition

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Writing and Balancing Chemical Equations

• To describe a reaction accurately, a chemical
  equation must show the same number of each type
  of atom on both sides of the equation.

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Writing and Balancing Chemical Equations

• CO2

Subscript IDENTIFIES THE NUMBER OF ATOMS IN A
COMPOUND.
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Writing and Balancing Chemical Equations cont

• Mg O2 ? MgO

2
2
Coefficient is the number in front of the
chemical formula that represents the of
molecules.
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H2 N2
NH3
?
3
2
HgO Cl2
HgCl O2
?
2
2
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Balancing Chemical Equations

• Magnesium (Mg) reacts with oxygen gas (O2),
  forming magnesium oxide (MgO). To write a
  balanced equation for this reaction, first write
  the equation using the formulas of the reactants
  and products, then count the number of atoms of
  each element.

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Balancing Chemical Equations

• Balancing Chemical Equations
• Balance the equation for the reaction of sodium
  metal (Na) with oxygen gas (O2), forming sodium
  oxide (Na2O).

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• Balancing Chemical Equations
• Balance the equation for the reaction of tin (Sn)
  with chlorine gas (Cl2), forming tin chloride
  (SnCl2).

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BALANCING equations
BALANCING EQUATIONS
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Please select a Team.

1. Team 1
2. Team 2
3. Team 3
4. Team 4
5. Team 5
6. Team 6
7. Team 7
8. Team 8

82
H2 N2 ? NH3

1. 4H2 2N2 ? NH3
2. 3H2 N2 ? 2NH3
3. 6H2 N2 ? 2NH3

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What type of do both of these compounds have?H2
N2 ? NH3

1. Ionic
2. Covalent

84
Ag2O ? Ag O2

1. 2Ag2O ? 4Ag O2
2. Ag2O ? Ag O2
3. 2Ag2O ? 2Ag 3O2

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Team Scores
3 Team 2
2.75 Team 3
2.6 Team 1
2.5 Team 4
2.5 Team 7
2.25 Team 6
2 Team 8
1.5 Team 5


86
What type of bond does Ag2O have?

1. Ionic
2. Covalent

87
Cl2 NaBr ? NaCl Br2

1. 2Cl2 2NaBr ? 2NaCl 2Br2
2. Cl2 NaBr ? NaCl Br2
3. Cl2 2NaBr ? 2NaCl Br2

88
What are the reactants? Cl2 NaBr ? NaCl Br2

1. Cl2 NaBr
2. NaCl Br2

89
Why do we balance equations?

1. Law of Conservation of Matter/Mass
2. Because energy is released.
3. Because mass changes in a reaction.

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Team Scores
7 Team 2
6.5 Team 4
6.25 Team 3
6.25 Team 7
6 Team 1
5.5 Team 6
5 Team 8
4.5 Team 5


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Acids and Bases

• Acid Tastes sour, react with metals and turns
  litmus paper red.
• Base Bitter, feels slippery and turns litmus
  paper blue.

92
pH

• A scale that measures whether a chemical solution
  is acidic or basic.

93
pH Scale

• The pH scale is from 0-14, 14 being basic, 0
  being acidic and 7 being neutral.

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Carbon plays an important role in living
organisms because it has a unique ability to bond
with other elements in many ways.

• Carbon Chemistry

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Almost all living things contain carbon. As a
result, they are known as organic compounds

• Organic Compounds

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Polymers

• Organic compounds are often found as polymers.
• A polymer is made of many molecules (monomers)
  attached together as one large molecule
  (polymer).
• Examples plastics, nylon, Teflon, proteins

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100
If a solution has a pH of 2.5 its

1. Acidic
2. Basic
3. neutral

101
If a solution has a pH of 11.5 its

1. Acidic
2. Basic
3. neutral

102
A polymer is

1. Many atoms connected together.
2. Many molecules connected together as one big
   molecule.

103
What type of reaction is this? Fe O2 ? Fe2O3

1. Synthesis
2. decomposition
3. replacement

104
Which one is balanced?Fe O2 ? Fe2O3

1. Fe O2 ? Fe2O3
2. 4Fe 3O2 ? 2Fe2O3
3. 2Fe 2O2 ? 2Fe2O3

105
Which one is balanced?P O2 ? P2O5

1. 2P 3O2 ? 4P2O5
2. 1P 4O2 ? 2P2O5
3. 4P 5O2 ? 2P2O5

106
What are the reactants?P O2 ? P2O5

1. P O2
2. P2O5

107
What color does a base turn litmus paper?

1. Purplish-magenta
2. Greenish-blue
3. Reddish-orange

108
What changes during a chemical reaction?

1. mass
2. Number of atoms
3. Chemical properties