Whats the Matter

1
Whats the Matter?
Interest Grabber
Section 2-1

• All of the materials around you are made up of
  matter. You are made up of matter, as are the
  chair you sit on and the air you breathe.
• 1. Give an example of solid matter.
• 2. Give an example of liquid matter.
• 3. Give an example of gaseous matter.
• 4. Is all matter visible?
• 5. Does all matter take up space?

2
Section Outline
Section 2-1

• 21 The Nature of Matter
• A. Atoms
• B. Elements and Isotopes
• 1. Isotopes
• 2. Radioactive Isotopes
• C. Chemical Compounds
• D. Chemical Bonds
• 1. Ionic Bonds
• 2. Covalent Bonds
• 3. Van der Waals Forces

3

• Matter anything that occupies space and has
  mass
• Mass measure of the amount of matter in an
  object

4
States of Matter

• Solid particles tightly linked, vibrate, fixed
  shape and volume
• Liquid particles more loosely linked, greater
  movement of particles, takes shape of container,
  fixed volume

5

• Gas particles have little or no attraction to
  each other, move most rapidly, fill volume of
  container

6

• A. Atom smallest particle of matter that can
  exist and still have the properties of a
  particular kind of matter (element)
• Elements and Isotopes

7

• Element substance consisting entirely of one
  type of atom
• Isotopes atoms of the same element have the
  same number of protons but the number of neutrons
  varies

8

• Radioactive isotopes isotopes with unstable
  nuclei the atoms break down at a constant rate
  over time

9
Structure of Atoms

• Nucleus in atoms, the center, which contains
  protons and neutrons and accounts for 99.9 of
  the atoms mass
• Proton positively charged subatomic particle
  located in the nucleus

10

• Neutron subatomic particle that is electrically
  neutral and is located in the atomic nucleus
• Atomic number number of protons in the nucleus
  of an atom identifies each element

11

• Electron negatively charged subatomic particle
  located outside the atomic nucleus
• high energy particles with very little mass
• move rapidly around nucleus at different levels

12

• outer level electrons have more energy
• 1st level holds up to 2 electrons
• 2nd level holds up to 8 electrons

13
An Element in the Periodic Table
Section 2-1
6
C
Carbon
12.011
14
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Figure 2-2 Isotopes of Carbon
Section 2-1
Nonradioactive carbon-12
Nonradioactive carbon-13
Radioactive carbon-14
6 electrons 6 protons 6 neutrons
6 electrons 6 protons 8 neutrons
6 electrons 6 protons 7 neutrons
16
C. Chemical Compounds

• Compound a substance formed by the chemical
  combination of two or more elements in definite
  proportions

17

• Eg H2O formula for water in a 21 ratio of
  hydrogen to oxygen
• H2SO4 formula for sulfuric acid in a 214
  ratio of hydrogen to sulfur to oxygen

18
D. Chemical Bonds

• 1. Ionic bond chemical bond that involves the
  transfer of electrons a bond formed by
  electrical attraction between two oppositely
  charged ions

19
Figure 2-3 Ionic Bonding
Section 2-1
Sodium atom (Na)
Chlorine atom (Cl)
Sodium ion (Na)
Chloride ion (Cl-)
Transfer of electron
Protons 11 Electrons -11 Charge 0
Protons 17 Electrons -17 Charge 0
Protons 11 Electrons -10 Charge 1
Protons 17 Electrons -18 Charge -1
20
Figure 2-3 Ionic Bonding
Section 2-1
Sodium atom (Na)
Chlorine atom (Cl)
Sodium ion (Na)
Chloride ion (Cl-)
Transfer of electron
Protons 11 Electrons -11 Charge 0
Protons 17 Electrons -17 Charge 0
Protons 11 Electrons -10 Charge 1
Protons 17 Electrons -18 Charge -1
21
Ionic Bonding
22
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23
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24
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25

• 2. Covalent bond chemical bond formed by two
  atoms sharing one or more pairs of electrons
• Molecule two or more atoms covalently bonded

26
Covalent Bonding
27
3. Van der Waals Forces

• A slight attraction that develops between the
  oppositely charged regions of nearby molecules

28
Water, Water Everywhere
Interest Grabber
Section 2-2

• If you have ever seen a photograph of Earth from
  space, you know that much of the planet is
  covered by water. Water makes life on Earth
  possible. If life as we know it exists on some
  other planet, water must be present to support
  that life.

29
Interest Grabber continued
Section 2-2

• 1. Working with a partner, make a list of ten
  things that have water
• in them.
• 2. Exchange your list for the list of another
  pair of students. Did your lists contain some of
  the same things? Did anything on the other list
  surprise you?
• 3. Did either list contain any living things?

30
Section Outline
Section 2-2

• 22 Properties of Water
• A. The Water Molecule
• 1. Polarity
• 2. Hydrogen Bonds
• B. Solutions and Suspensions
• 1. Solutions
• 2. Suspensions
• C. Acids, Bases, and pH
• 1. The pH Scale
• 2. Acids
• 3. Bases
• 4. Buffers

31
A. The Water Molecule

• 1. Polarity
• H and O atoms are covalently bonded
• O with 8 protons has a greater charge than H
  with only 1 proton

32

• O pulls shared electrons toward its nucleus due
  to the greater charge attracting the
  electrons
• Electrical charge is not evenly distributed

33

• The O region is weakly negative
• The H regions are weakly positive
• Water is a polar compound due to the uneven
  distribution of charges.

34

• This makes it a good solvent for other polar
  compounds such as sugar, some proteins
• Also good at dissolving ionic compounds such as
  NaCl

35
http//www.luminet.net/wenonah/hydro/h2o.htm
36
http//www.luminet.net/wenonah/hydro/h2o.htm
37
2. Hydrogen bonds

• Because water is polar, the molecules are
  attracted to one another.
• 2 water molecules are held together by hydrogen
  bonding
• A hydrogen bond is formed

38

• between the hydrogen region of one molecule and
  the oxygen region of another molecule
• Hydrogen bonds are weak and easily broken

39

• H bonds cause water to stick to itself and other
  substances.
• Cohesion attraction of like molecules to each
  other
• Ex surface tension of water
• Adhesion attraction of unlike substances to
  each other

40

• Adhesion cohesion together let water exhibit
  capillary action
• Capillary action the reaction of a liquid
  surface with a solid lets water move up the
  inside of a narrow tube against gravity

41
Solutions and Suspensions1. Solutions

• Mixture two or more elements or compounds
  physically mixed together but not chemically
  combined

42

• Solution - a mixture in which one or more
  substances are uniformly dissolved in another
  substance
• Solute a substance dissolved in a solution

43

• Solvent in a solution, the substance in which a
  solute is dissolved
• Ex water universal solvent
• Concentration measurement of the amount of
  solute dissolved in a fixed amount of solution

44

• Saturated solution one in which no more solute
  can dissolve
• Aqueous solutions solutions with water as the
  solvent water is the universal solvent

45
2. Suspensions

• Mixture of water and nondissolved materials the
  nondissolved materials have particles so small,
  they do not settle out

46
C. Acids, Bases, and pH

• 1. The pH Scale to show the concentration of H
  (hydrogen) ions in solution
• OH- is a hydroxide ion.

47
pH scale potential hydrogen scale

• The pH scale is logarithmic.
• A change of one pH unit a 10X change in the
  strength of the acid or base.

48

• The higher the above 7, the stronger the base.
• The lower the below 7, the stronger the acid.
• 7 is neutral

49
2. Acids

• A compound that forms hydrogen ions H in
  solution
• Have higher concentrations of hydrogen ions than
  pure water
• pH is below 7

50

• Dissociation breaking apart of water molecule
  into 2 ions of opposite charge
• H2O ? H OH-

51
3. Base

• A compound that makes hydroxide ions (OH-) in
  solution
• Bases have lower concentrations of H ions than
  pure water
• Bases have a pH above 7

52
4. Buffer

• Weak acid or base that can react with strong
  acids or bases to help prevent sharp, sudden
  changes in pH

53
pH Scale
Section 2-2
Oven cleaner
Bleach
Ammonia solution
Increasingly Basic
Soap
Sea water
Human blood
Neutral
Pure water
Milk
Normal rainfall
Acid rain
Increasingly Acidic
Tomato juice
Lemon juice
Stomach acid
54
Figure 2-9 NaCI Solution
Section 2-2
Cl-
Cl-
Na
Na
Water
Water
55
Figure 2-9 NaCI Solution
Section 2-2
Cl-
Cl-
Na
Na
Water
Water
56
Lifes Backbone
Interest Grabber
Section 2-3

• Most of the compounds that make up living things
  contain carbon. In fact, carbon makes up the
  basic structure, or backbone, of these
  compounds. Each atom of carbon has four electrons
  in its outer energy level, which makes it
  possible for each carbon atom to form four bonds
  with other atoms.
• As a result, carbon atoms can form long chains. A
  huge number of different carbon compounds exist.
  Each compound has a different structure. For
  example, carbon chains can be straight or
  branching. Also, other kinds of atoms can be
  attached to the carbon chain.

57
Interest Grabber continued
Section 2-3

• 1. On a sheet of paper, make a list of at least
  ten things that contain carbon.
• 2. Working with a partner, review your list. If
  you think some things on your list contain only
  carbon, write only carbon next to them.
• 3. If you know other elements that are in any
  items on your list, write those elements next to
  them.

58
Section Outline
Section 2-3

• 23 Carbon Compounds
• A. The Chemistry of Carbon
• B. Macromolecules
• C. Carbohydrates
• D. Lipids
• E. Nucleic Acids
• F. Proteins

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23 Carbon CompoundsA. The Chemistry of Carbon

• Organic chemistry - study of compounds that
  contain carbon and are usually associated with
  living things most organic compounds have bonds
  between carbon atoms

60

• Carbon - Carbon bonds can be single, double, or
  triple covalent bonds

61
B. Macromolecules

• Means giant molecules
• Made from thousands or hundreds of thousands of
  smaller molecules

62

• Formed by polymerization
• Smaller units, monomers, join together to form
  polymers

63

• Biomolecules (organic molecules found in living
  things) include carbohydrates, lipids, proteins,
  and nucleic acids

64
Concept Map
Section 2-3
Carbon Compounds
include
that consist of
that consist of
that consist of
that consist of
which contain
which contain
which contain
which contain
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Carbon is Unique!

• Forms a variety of covalent bonds that are strong
  and stable
• Has 4 electrons in its second energy level
• Can form 4 single covalent bonds

66

• Can also form double and triple bonds
• Can form long chains by bonding with other carbon
  atoms
• Can form rings

67
C. Carbohydrates

• Made up of carbon, hydrogen, and oxygen with the
  monomer in the ratio of 121
• Hydrogen and Oxygen are in a 21 ratio in all
  carbohydrates

68

• Carbohydrates are the main sources of energy for
  living things
• Plants and some animals also use carbohydrates
  structurally

69
Monosaccharides

• Single sugar molecules
• Chemical formula C6H12O6
• Ex glucose, fructose, galactose

70
Isomers

• Have the same chemical formula but different
  structural formula

71
Structural formula for glucose
http//www.borg.com/lubehawk/biochem.htm
72
Monosaccharide Isomers C6H12O6
http//www.purchon.com/biology/sugars.htm
73
Dehydration Synthesis

• Monosaccharides are combined to form larger
  molecules by a process of polymerization
• A bond forms between each simple sugar at the OH
  groups

74

• A water molecule is removed where the bond forms
  between the 2 monosaccharides
• Since an HOH is pulled out, or one water
  molecule, the process is called dehydration
  synthesis

75
Dehydration Synthesis

• Reaction in which small molecules join to form a
  large molecule, removing water in the process
• Dehydration means loss of water
• Synthesis means putting together

76
Disaccharides

• form as a result of dehydration synthesis
  between 2 monosaccharides  (ex maltose,
  sucrose)

77
http//www.purchon.com/biology/sugars.htm
C12 H22O11, sucrose, formed as a result of
dehydration synthesis This is table sugar.
78
http//homepages.ius.edu/GKIRCHNE/biomolec.htm
79
http//faculty.clintoncc.suny.edu/faculty/Michael.
Gregory/files/Bio20101/Bio2010120Lectures/Bioch
emistry/biochemi.htm
80

• Sucrose
• This is called a condensation or dehydration
  synthesis reaction

http//faculty.clintoncc.suny.edu/faculty/Michael.
Gregory/files/Bio20101/Bio2010120Lectures/Bioch
emistry/biochemi.htm
81
Hydrolysis

• A catabolic reaction that splits apart larger
  molecules into smaller ones with the consumption
  of water
• Hydrolysis means water splitting

82
Hydrolysis
http//campus.northpark.edu/biology/cell/chemreact
.html
83
Polysaccharides

• 3 or more connected monosaccharides (ex starch,
  glycogen, chitin, cellulose
• Animals store excess sugar in the form of the
  polysaccharide glycogen

84

• Plants store excess sugar in the form of the
  polysaccharide starch
• Cellulose, another polysaccharide is used by
  plants for strength and rigidity

85
Figure 2-11 Carbon Compounds
Section 2-3
Methane
Acetylene
Butadiene
Benzene
Isooctane
86
THE DEHYDRATION SYNTHESIS OF MALTOSE FROM TWO
GLUCOSE MOLECULES

THE DEHYDRATION SYNTHESIS OF MALTOSE FROM TWO
GLUCOSE MOLECULES                               
                                                  
                                                  
                                                  
                                                  
                                                  
                                          
http//www.borg.com/lubehawk/biochem.htm
87
Figure 2-13 A Starch
Section 2-3
Starch
Glucose
88
D. Lipids

• Not soluble in water
• Contain many carbon and hydrogen atoms, and a few
  oxygen atoms
• Can store energy

89

• Are important parts of biological membranes and
  waterproof coverings
• Steroids are chemical messengers and are lipids

90
Building Blocks of Lipids

• Fatty Acid

Glycerol
http//www.borg.com/lubehawk/biochem.htm
91

• When a glycerol molecule and 3 fatty acid
  molecules are bonded together as a result of
  dehydration synthesis, a lipid molecule is formed

92
Dehydration Synthesis to form a lipid molecule
http//www.borg.com/lubehawk/biochem.htm
93
Saturated Fats

• If all carbon atoms are bonded to the next carbon
  atom in the fatty acid chains with only single
  bonds, it is saturated with the most hydrogen
  atoms possible

94
Monounsaturated Fat

• If there is one carbon-carbon double bond in a
  fatty acid chain, it is a monounsaturated Fat

95
Polyunsaturated fat

• If a fatty acid chain contains several double
  carbon-carbon bonds, it is a polyunsaturated fat
• Unsaturated fats are liquid at room temperature

96
E. Nucleic Acids

• Macromolecules containing hydrogen, oxygen,
  nitrogen, carbon, and phosphorus
• Polymers made up of monomers called nucleotides
  the building blocks of nucleic acids

97

• Nucleotides are made up of 3 parts
• a 5-carbon sugar
• a phosphate group
• a nitrogenous base

98
Nucleotides Building
Blocks of a Nucleic Acid

• One nucleotide consists of a 5 carbon sugar, a
  phosphate group, and a nitrogenous base

http//www.borg.com/lubehawk/biochem.htm
99
DNA Deoxyribonucleic Acid

• 5-carbon sugar Deoxyribose
• Phosphate group
• Either Adenine, Thymine, Guanine, or Cytosine 4
  possible nitrogenous bases

100
RNA Ribonucleic Acid

• 5-carbon sugar Ribose
• Phosphate group
• Either Adenine, Uracil, Guanine, or Cytosine 4
  possible nitrogenous bases

101
Nucleic Acids

• Store and transmit genetic information

102
F. Proteins

• Macromolecules that are made of many amino acids
  bonded together

103
Amino Acids

• Each amino acid is made up of
• an amino group (-NH2) on one end
• a carboxyl group (-COOH) on the other end

104

• a central carbon atom
• a side chain called an R-group
• The R-groups are varied in composition and
  account for the 20 different types of amino acids

105

• Some R-groups are acidic, some basic, some polar,
  some nonpolar
• Some have carbon rings

106

• DNA provides the instructions for putting the
  amino acids into a specific order to make
  specific proteins
• Each protein does a specific job

107
Proteins

• Control rate of reactions
• Regulate cell processes
• Form bones and muscles
• Transport substances into or out of cells

108

• Help fight disease antibodies are proteins
• Most enzymes are proteins

109
Levels of Organization of Proteins

• 1st level primary - amino acid sequence
• 2nd level - secondary - amino acids within a
  chain can be twisted or folded

110

• 3rd level - tertiary - the chain is folded
• 4th level - quaternary - if there is more than
  one chain, each chain has a specific arrangement

111

• Hydrogen bonds and Van der Waals forces help keep
  a proteins shape

112
Figure 2-16 Amino Acids
Section 2-3
Amino group
Carboxyl group
General structure
Alanine
Serine
113
Figure 2-16 Amino Acids
Section 2-3
Amino group
Carboxyl group
General structure
Alanine
Serine
114
Figure 2-16 Amino Acids
Section 2-3
Amino group
Carboxyl group
General structure
Alanine
Serine
115

• Peptide bond a type of covalent bond that holds
  amino acids together in protein molecules
• Dipeptide - two amino acids bonded together
• Polypeptide - 3 or more amino acids bonded
  together

116
Dehydration Synthesis to form a Dipeptide
http//www.borg.com/lubehawk/biochem.htm
117
Figure 2-17 A Protein
Section 2-3
Amino acids
118
Matter and Energy
Interest Grabber
Section 2-4

• Have you ever sat around a campfire or watched
  flames flicker in a fireplace? The burning of
  wood is a chemical reactiona process that
  changes one set of chemicals into another set of
  chemicals. A chemical reaction always involves
  changes in chemical bonds that join atoms in
  compounds. The elements or compounds that enter
  into a chemical reaction are called reactants.
  The elements or compounds produced by a chemical
  reaction are called products. As wood burns,
  molecules of cellulose are broken down and
  combine with oxygen to form carbon dioxide and
  water vapor, and energy is released.

119
Interest Grabber continued
Section 2-4

• 1. What are the reactants when wood burns?
• 2. What are the products when wood burns?
• 3. What kinds of energy are given off when wood
  burns?
• 4. Wood doesnt burn all by itself. What must you
  do to start a fire? What does this mean in terms
  of energy?
• 5. Once the fire gets started, it keeps burning.
  Why dont you need to keep restarting the fire?

120
Section Outline
Section 2-4

• 24 Chemical Reactions and Enzymes
• A. Chemical Reactions
• B. Energy in Reactions
• 1. Energy Changes
• 2. Activation Energy
• C. Enzymes
• D. Enzyme Action
• 1. The Enzyme-Substrate Complex
• 2. Regulation of Enzyme Activity

121

• 24 Chemical Reactions and Enzymes
• A. Chemical Reaction -

any process in which a chemical change occurs
122

• Reactants elements or compounds that enter into
  a chemical reaction
• Products elements or compounds produced by a
  chemical reaction

123

• Chemical reactions always involve the breaking of
  bonds in reactants and the formation of new bonds
  in products

124

• A chemical equation is used to represent a
  chemical reaction
• Ex
• CO2 H20 ? H2CO3
• H2CO3 ? CO2 H2O

125

• Carbon dioxide forms carbonic acid in your
  bloodstream where it reacts with water in the
  lungs it changes back to carbon dioxide and water

126

• Reactants are on the left side of the equation
• Products are on the right side
• The numbers of atoms of each kind must be the
  same on both sides of the equation

127
B. Energy in Reactions

• Energy Changes chemical reactions either
  release energy or absorb energy
• Energy releasing reactions can occur
  spontaneously

128

• Energy is released in the form of heat energy and
  sometimes as light and sound energy (when
  hydrogen gas explodes)
• Ex hydrogen gas reacting with oxygen to yield
  water vapor
• 2H2 O2 ? 2H2O

129

• Energy absorbing reactions need a source of
  energy
• Ex when water is changed into hydrogen and
  oxygen gas
• 2H2O ? 2H2 O2

130

• All organisms must carry out reactions that need
  energy in order to stay alive
• Plants get energy by trapping sunlight for
  photosynthesis and storing energy in compounds
  produced

131
2. Activation Energy

• Energy that is need to get a reaction started

132
C. Enzymes

• Enzymes are organic catalysts they speed up
  reactions in organisms
• Catalysts speed up the rate of chemical reactions
  by lowering the activation energy

133
D. Enzyme Action

• Reactants must collide with enough energy to
  break old bonds and form new ones

134
1. The Enzyme-Substrate Complex

• Active site - the place on the enzyme where
  reactants (substrates) are brought together to
  react

135
Substrate

• The substance on which an enzyme acts
• The Enzyme-Substrate Complex formed when an
  enzyme joins with a substrate

136
Figure 2-21 Enzyme Action
Section 2-4
Enzyme (hexokinase)
Glucose
Substrates
ADP
Products
Glucose-6- phosphate
ATP
Products are released
Active site
Substrates bind to enzyme
Enzyme-substrate complex
Substrates are converted into products
137
Figure 2-21 Enzyme Action
Section 2-4
Enzyme (hexokinase)
Glucose
Substrates
ADP
Products
Glucose-6- phosphate
ATP
Products are released
Active site
Substrates bind to enzyme
Enzyme-substrate complex
Substrates are converted into products
138
Figure 2-21 Enzyme Action
Section 2-4
Enzyme (hexokinase)
Glucose
Substrates
ADP
Products
Glucose-6- phosphate
ATP
Products are released
Active site
Substrates bind to enzyme
Enzyme-substrate complex
Substrates are converted into products
139
Figure 2-21 Enzyme Action
Section 2-4
Enzyme (hexokinase)
Glucose
Substrates
ADP
Products
Glucose-6- phosphate
ATP
Products are released
Active site
Substrates bind to enzyme
Enzyme-substrate complex
Substrates are converted into products
140
2. Regulation of Enzyme Activity

• Work best at specific temperature (close to 370C
  in humans) and pH 7
• Specific proteins can turn key enzymes on or
  off

141
Effect of Enzymes
Section 2-4
Reaction pathway without enzyme
Activation energy without enzyme
Activation energy with enzyme
Reactants
Reaction pathway with enzyme
Products
142
Figure 2-19 Chemical Reactions
Section 2-4
Energy-Releasing Reaction
Energy-Absorbing Reaction
Activation energy
Products
Activation energy
Reactants
Reactants
Products
143
Figure 2-19 Chemical Reactions
Section 2-4
Energy-Releasing Reaction
Energy-Absorbing Reaction
Activation energy
Products
Activation energy
Reactants
Reactants
Products
144
Video Contents
Videos

• Click a hyperlink to choose a video.
• Atomic Structure
• Energy Levels and Ionic Bonding
• Covalent Bonding
• Enzymatic Reactions

145
Video 1
Video 1
Atomic Structure

• Click the image to play the video segment.

146
Video 2
Video 2
Energy Levels and Ionic Bonding
Click the image to play the video segment.
147
Video 3
Video 3
Covalent Bonding
Click the image to play the video segment.
148
Video 4
Video 4
Enzymatic Reactions
Click the image to play the video segment.
149
Internet
Go Online

• Career links on forensic scientists
• Interactive test
• Articles on organic chemistry
• For links on properties of water, go to
  www.SciLinks.org and enter the Web Code as
  follows cbn-1022.
• For links on enzymes, go to www.SciLinks.org and
  enter the Web Code as follows cbn-1024.

150
Section 1 Answers
Interest Grabber Answers

• 1. Give an example of solid matter.
• Sample answers books, desks, chairs
• 2. Give an example of liquid matter.
• Sample answers water, milk
• 3. Give an example of gaseous matter.
• Sample answers air, helium in a balloon
• 4. Is all matter visible?
• No
• 5. Does all matter take up space?
• Yes

151
Section 2 Answers
Interest Grabber Answers

• 1. Working with a partner, make a list of ten
  things that have water in them.
• Possible answers bodies of water, rain and
  snow, soft drinks and other beverages, juicy
  foods such as fruits, and so on.
• 2. Exchange your list for the list of another
  pair of students. Did your lists contain some of
  the same things? Did anything on the other list
  surprise you?
• Students answers will likely be similar, but
  not exactly alike.
• 3. Did either list contain any living things?
• Students lists may include plants, animals, or
  other living things.

152
Section 3 Answers
Interest Grabber Answers

• 1. On a sheet of paper, make a list of at least
  ten things that contain carbon.
• Students will likely know that charcoal and coal
  contain carbon. They may also list carbohydrates
  (starches and sugars), oil, gasoline, wood, or
  carbon dioxide.
• 2. Working with a partner, review your list. If
  you think some things on your list contain only
  carbon, write only carbon next to them.
• Students will say that charcoal and coal contain
  only carbon. While these materials do contain
  small amounts of other elements, such as sulfur,
  they are composed mostly of carbon.
• 3. If you know other elements that are in any
  items on your list, write those elements next to
  them.
• Students may know that many carbon compounds
  also contain oxygen and/or hydrogen.

153
Section 4 Answers
Interest Grabber Answers
1. What are the reactants when wood
burns? Reactants are oxygen and cellulose. 2.
What are the products when wood burns? Products
are carbon dioxide and water. 3. What kinds of
energy are given off when wood burns? Light and
heat are given off. Some students may also
mention sound (the crackling of a fire). 4. Wood
doesnt burn all by itself. What must you do to
start a fire? What does this mean in terms of
energy? To start a fire, you must light it with
a match and kindling. You are giving the wood
some energy in the form of heat. 5. Once the fire
gets started, it keeps burning. Why dont you
need to keep restarting the fire? Once the fire
gets going, it gives off enough heat to start
more of the wood burning.
154
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