1. Welcome !!!! Dr. Leslie Sombers leslie_sombers@ncsu.edu Lingjiao Qi
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Copyright © Houghton Mifflin Company.All rights reserved.

3. Your assignment:
A. Develop a thinking map or brainstorm a list to show what you know about Chemistry.
B. Share your map with your group/neighbor.
C. Place your map on the wall.
D. With your group, develop a definition for chemistry. Write it on your sentence strip and post it for others to see.

4. The study of all substances and the CHANGES they undergo.
What is Chemistry?
The study of all substances and the CHANGES they undergo.
Referred to as the Central Science because it overlaps so many other sciences.
It all begins with curiosity!
The study of matter and energy and the intxns between them.
Imagine an activity that does NOT directly or indirectly depend on chemistry –
Cooking? Playing golf? Brushing teeth? Farming? Computer work? Banking? Teaching 3rd grade teachers? Voting?
All depend on chemistry or chemicals in some way.

5. Pre- test To assess content knowledge and learning…..
Sorry guys, it’s a requirement!!!!
Copyright © Houghton Mifflin Company.All rights reserved.

6. Some Definitions…. Hypothesis:
Theory:
Variable:
Fact:
Law:
a proposed explanation for a phenomenon. Generally based on observations
Hypothesis that has been tested over long periods
a value that may change within the scope of a given problem
A hypothesis (plural hypotheses) is a proposed explanation for a phenomenon. Generally based on observations
In mathematics, a variable is a value that may change within the scope of a given problem or set of operations.[
Fact – something that is true. Scientific facts are verified by repeatable experiments.
Law - A scientific law is a statement based on repeated experimental observations that describes some aspect of the world.
Valid observation. Scientific facts are verified by repeatable experiments.
A scientific law is a statement based on repeated experimental observations that describes some aspect of the world.

7. Classifying Matter
Matter is classified by the number of phases it contains.
Any part of a system with uniform composition and properties is called a phase.
Matter can be classified as either Homogeneous or Heterogeneous.

8. Mixtures Mixtures are a physical blend of 2 or more kinds of matter.
Mixtures can be either homogeneous (solutions) or heterogeneous.
Separation of mixtures is done by physical means such as magnets, distillation, chromatography and filtration.

9. Pure Substances
A pure substance has a fixed composition . Elements and compounds are pure substances.
Unlike mixtures, every sample of a pure substance has exactly the same characteristic properties and composition.
^*#{}#*^
SHOW Robby, Robby.acs, 50,50
PLAY DontRecognize
MOVE 50,50
SAYNOCAP Matter that is uniform and has definite composition is called a substance. Substances contain only one type of matter.
SLIDE 5=SAYNOCAP Lets look at examples of physical properties

10. Elements and Compounds
An element is a collection of the same type of atom. They are the simplest form of matter that can exist under normal lab conditions. Compounds consist of two or more elements that are chemically combined. They can be separated only by a chemical change.
Making a compound….

11. Extensive vs. Intensive
Extensive Properties
Depend on the amount of matter present
Mass, volume, length, height, amount of energy, etc.
Intensive Properties
Do not depend on the amount of matter present
Density, boiling point, melting point, color, ability to conduct electricity, etc.

12. Metric System
The metric system is based on a base unit that corresponds to a certain kind of measurement
Length = meter
Volume = liter
Weight (Mass) = gram
Prefixes plus base units make up the metric system
Example:
Centi + meter = Centimeter
Kilo + liter = Kiloliter

13. Metric System How do you remember all of them?
The three prefixes that we will use the most are:
Kilo= 1000
centi = 1/100 (one hundredth)
milli= 1/1000 (one thousandth)
How do you remember all of them?
Kissing Hairy Dark space dogs causes mono
King Henry Died by Drinking Chocolate Milk
Kilo
(1000)
Hecto
(100)
Deca
(10)
Base Units
meter
gram
liter
deci
(1/10)
centi
(1/100)
milli
(1/1000)

14. Metric System 1.5 meters 5 meters 10 miles = 16093 meters
So if you needed to measure length you would choose meter as your base unit
Length of a tree branch
1.5 meters
Length of a room
5 meters
But what if you need to measure a longer distance, like from your house to school?
Let’s say you live approximately 10 miles from school
10 miles = meters
16093 is a big number, but what if you could add a prefix onto the base unit to make it easier to manage:
16093 meters = kilometers (or 16.1 if rounded to 1 decimal place)

15. Metric System
These prefixes are based on powers of 10. What does this mean?
From each prefix every “step” is either:
10 times larger or
10 times smaller
For example
Centimeters are 10 times larger than millimeters
1 centimeter = 10 millimeters
Kilo
(1000)
Hecto
(100)
Deca
(10)
Base Units
meter
gram
liter
deci
(1/10)
centi
(1/100)
milli
(1/1000)

16. Metric System
Centimeters are 10 times larger than millimeters so it takes more millimeters for the same length
1 centimeter = 10 millimeters
Example not to scale 40 41
1 mm 40 41
1 cm

17. Metric System For each “step” to right, you are multiplying by 10
For example, let’s go from a base unit to centi
1 liter = 10 deciliters = 100 centiliters
2 grams = 20 decigrams = 200 centigrams
( 1 x 10 = 10) = (10 x 10 = 100)
(2 x 10 = 20) = (20 x 10 = 200)
Kilo
(1000)
Hecto
(100)
Deca
(10)
Base Units
meter
gram
liter
deci
(1/10)
centi
(1/100)
milli
(1/1000)

18. Metric System
An easy way to move within the metric system is by moving the decimal point one place for each “step” desired
Example: change meters to centimeters
1 meter = 10 decimeters = 100 centimeters or
1.00 meter = 10.0 decimeters = 100. centimeters
Kilo
(1000)
Hecto
(100)
Deca
(10)
Base Units
meter
gram
liter
deci
(1/10)
centi
(1/100)
milli
(1/1000)

19. Metric System
Now let’s try our previous example from meters to kilometers:
16093 meters = decameters = hectometers = kilometers
So for every “step” from the base unit to kilo, we moved the decimal 1 place to the left (the same direction as in the diagram below)
Kilo
(1000)
Hecto
(100)
Deca
(10)
Base Units
meter
gram
liter
deci
(1/10)
centi
(1/100)
milli
(1/1000)

20. Metric System
If you move to the left in the diagram, move the decimal to the left
If you move to the right in the diagram, move the decimal to the right
Kilo
(1000)
Hecto
(100)
Deca
(10)
Base Units
meter
gram
liter
deci
(1/10)
centi
(1/100)
milli
(1/1000)

21. Metric System
Now let’s start from centimeters and convert to kilometers
centimeters = ? kilometers
Kilo
(1000)
Hecto
(100)
Deca
(10)
Base Units
meter
gram
liter
deci
(1/10)
centi
(1/100)
milli
(1/1000)

22. Metric System Now let’s start from meters and convert to centimeters
5 meters = ? centimeters
Kilo
(1000)
Hecto
(100)
Deca
(10)
Base Units
meter
gram
liter
deci
(1/10)
centi
(1/100)
milli
(1/1000)
Now let’s start from kilometers and convert to meters
.3 kilometers = ? meters
Kilo
(1000)
Hecto
(100)
Deca
(10)
Base Units
meter
gram
liter
deci
(1/10)
centi
(1/100)
milli
(1/1000)

23. Metric System
Summary
Base units in the metric system are meter, liter, gram
Metric system is based on powers of 10
For conversions within the metric system, each “step” is 1 decimal place to the right or left
Using the diagram below, converting to the right, moves the decimal to the right and vice versa
Kilo
(1000)
Hecto
(100)
Deca
(10)
Base Units
meter
gram
liter
deci
(1/10)
centi
(1/100)
milli
(1/1000)

24. Standard Metric Prefixes for the SI Units
Copyright © Houghton Mifflin Company.All rights reserved.

25. Matter POGIL
The structure of matter

26. ACS – Inquiry in Action. A guided-inquiry approach.
Purpose: to provide a set of physical science activities to help teach major concepts in the study of matter and to help students develop their abilities in scientific inquiry
Developed to work across grades 3-8
Cover basic concepts with flexibility incorporated
Common, safe and inexpensive materials
Material is based on the National Science Education Content Standards for Physical Science and Science as Inquiry
Scientific questions are their investigation
Physical properties
Physical change
Dissolving solids, liquids and gases
Chemical change
States of matter
Density
To be effective over such a wide range, they cover basic concepts but have the flexibility to be modified through various questioning strategies, the degree of guidance given to students, and the vocabulary used.

27. Each investigation
Begins with an intro activity to motivate discussion
Together, teacher and students develop a question to investigate and design an experiment to answer the question
Students plan their experiment, record their results, and draw conclusions.
Teachers should involve students as much as possible in the entire process of conducting a scientific investigation.
Whenever possible, students own questions and interests should initiate an investigation.
Teachers help students identify and communicate the thought processes involved in designing and conducting an investigation.
Goal: students will acquire both the skills of scientific inquiry and the concepts of the physical science curriculum

28. Essential Features of Inquiry:
Students begin with a question that can be answered in a scientific way
Students rely on evidence in attempting to answer the question
Students form an explanation to answer the question based on the evidence collected
Students evaluate their explanation

29. Science as inquiry: Abilities necessary to do scientific inquiry

30. Science as inquiry: Understandings about scientific inquiry

31. Physical science content standards
The Standards place most topics traditionally considered chemistry-related under the physical science content standard of ‘Properties of objects and materials’ for Grads K-4 and ‘Properties and changes of properties in matter’ for Grades The topics addressed under these content standards are summarized in the chart

32. Question to investigate
A question at the beginning of each activity serves as a guide for designing and conducting
the experiments to answer that question. All the activities within an investigation
lead up to or contribute to the overall objective of the investigation.
Procedure
Procedures are examples or models of ways to design and conduct an
experiment to answer the question to investigate. Because student input in the experimental
design is encouraged, the procedure may be modified or completely changed.
The procedure is offered as a guide to show one way an activity can be conducted.
Expected results
The expected results describe what would happen if the activities were
conducted exactly as written. These should be used as a guide, as the procedures students
develop may vary.
Activity sheets
Each activity has a corresponding activity sheet, which guides students as they conduct
the activity. The activity sheets help students plan their experiments, record
their observations, draw conclusions based on observations, offer explanations, and
apply their learning. When needed, the activity sheets also contain science content.
Assessment
One scoring rubric is included with each investigation. This can be used as a formative
assessment of the students’ work on the activity sheets and their performance
doing the hands-on activities that were a part of the investigation. A separate summative
assessment for the investigation, called Review and apply, is included at the
end of each investigation.
Many, if not all, of the properties of objects, materials, and substances listed in the chart can be explained
by referring to the atoms and molecules of which they are made. The types of atoms and molecules that
make up a substance and the arrangement and strength of the bonds between them determine the different
characteristic properties of that substance, including its physical properties and how it undergoes
physical and chemical change. But for students at the 3–8 grade level, for whom Inquiry in Action is written,
it is not necessary to focus primarily on the atomic and molecular explanation of why substances
have the properties or undergo change the way they do. Students can learn a great deal about the properties
and changes of properties in matter through their own direct macroscopic observations of the different
characteristics of substances and processes. In fact, the National Science Education Standards state: It can be tempting to introduce atoms and molecules
or improve students’ understanding of them so that particles can be used as an explanation for the properties
of elements and compounds. However, use of such terminology is premature for these students and can
distract from the understanding that can be gained from focusing on the observation and description of
macroscopic features of substances and of physical and chemical reactions (NSES, p. 149).

33. The Power of Polarity
Atoms have a certain number of protons in their nucleus and the same number of electrons around the nucleus.
Protons – POSITIVE CHARGE
Electrons – NEGATIVE CHARGE
Because the nucleus contains protons, it has an attraction for electrons.
Since an atom has the same number of positively-charged protons as negatively-charged electrons, an atom has no overall or net charge. IT IS NEUTRAL.
Water (H2O) is made up of 2 hydrogen atoms bonded
to one oxygen atom.
It is the special character of this oxygen-hydrogen bond
that makes water such a good dissolver O H H

34. Atoms can form a covalent bond
When 2 atoms get near each other, the protons in the nucleus of each atom have a certain attraction for the electrons in the other atom.
If the attractions are just right, one or more electrons from each atom can end up moving around the nuclei of BOTH atoms.
Even though the atoms in the water molecule share electrons, the total number of electrons is still equal to the total number of protons. Therefore, the water molecule has no overall or net charge.

35. - - + + The oxygen-hydrogen bond
Because the oxygen has a greater attraction for electrons than the hydrogens have, the electrons shared between the oxygen and hydrogen atoms spend more time around the oxygen than they do around the hydrogens.
Because electrons have a negative charge, this makes
the area around the oxygen atom slightly negatively charged. It also leaves the
area around the hydrogen atoms slightly positively charged. - - O O H H H H + +
BEFORE
AFTER

36. - - - - + + + + A picture of water O O H H H H
The charge density model
The space-filling model
In reality, the nucleus would be much
smaller in relation to the electron cloud around it. O H H
The ball and stick model

37. The power of polarity
The molecules in liquid water associate very closely with one another
They orient themselves according to their polarity (the positive area of one molecule is attracted to the negative area of another)
Attractions between water molecules are constantly breaking and new ones are forming with other water molecules
The attraction water molecules have for other polar or charged particles is what makes water so effective at dissolving many substances

38. The molecular structure of sucrose molecules
Sugar dissolves in water because of the special structure of the water molecule, but also because of the structure of the molecules that make up sugar (sucrose).
C12H22O11
Red = oxygen (slightly negative)
gray = hydrogen (slightly positive)

40. Dissolution – 2 sucrose molecules dissolving in water1 2
Notice how the positive areas of the water molecules (near the hydrogen atoms) are attracted to the negative area near the oxygen atoms on the sucrose. And the negatively charged areas of the water molecules (near the oxygen atoms) are attracted to the positive area near the hydrogen atoms on the sucrose.
The mutual attraction between the water and the sucrose molecules overcomes the attraction the sucrose molecules have for each other and they separate and dissolve. They become completely surrounded by water molecules, and move throughout the water.
It is both the polar nature of water and the polar nature of sucrose that explain why sugar dissolves in water. 3 4

42. Investigation 1: Scientific questions and their investigation
Key concepts for students
In a scientific experiment, a “variable” is something that can affect the outcome of the experiment.
When designing a scientific experiment, it is necessary to identify and control variables.
In an experiment to find out if a certain variable affects the outcome, only that variable should be allowed to vary and all other variables should be kept the same.
The temperature of a solvent affects the speed of dissolving.
Learning objectives
Students will be able to:
Ask scientific questions that they can investigate.
Identify and control variables as they design an experiment to answer the questions.
Be able to make predictions, design and conduct tests, record their observations, and draw logical
conclusions.
Understand the meaning of the “characteristic properties” of an object or substance.
Identify variables that affect dissolving.

43. Investigation 1: Scientific questions and their investigation
Investigation questions
What happens when the colored coating of an M&M gets wet?
What happens when one M&M is placed in water?
Do some M&M colors dissolve in water faster than others?
What would the colors look like if we place two or more M&M’s in a plate of water?
Is the “line” that forms when two colors meet a special property of M&M’s?
Does the temperature of the water affect how fast the colored coating dissolves from an M&M?
Does the amount of sugar already dissolved in water affect how fast an M&M coating dissolves?

44. Chemistry review: Water
A water molecule has no overall or “net” charge. It is neutral.
Because of the way oxygen and hydrogen are bonded together, water has an area of positive charge and an area of negative charge. This makes the water a polar molecule.
Because of water’s polarity, water molecules are attracted to each other.
Sugar (sucrose) also has oxygens and hydrogens bonded to each other. This gives sucrose many areas of positive and negative charge.
Water and sucrose are attracted to one another based on the attractions of opposite charges.
When the attraction that water molecules have for sucrose overcomes the attraction sucrose molecules have for each other, the sucrose dissolves.
The polar nature of water is what makes water so good at dissolving many substances.

45. The structure of water

46. Ion POGIL
Review - How are ions made from neutral atoms?
Yes
Yes no
metal
Yes
Yes no
metal
Yes no
nonmetal
Yes
Yes
Yes
nonmetal
Yes
Yes no

47. 2. What distinguishes a neutral atom from an ion?
A change in the number of electrons
3a. Where is the ion charge located in the isotope symbol?
Upper right
3b. Is a charge indicated on the neutral atoms? If yes, where is it located?
There is no charge indicated
4. Which subatomic particle carries a positive charge?
protons
5. Which subatomic particle carries a negative charge?
electrons
6. Propose a mathematical equation to calculate the charge on an ion from the number of protons and electrons in an ion. Confirm that your equation works using two positive ion examples and two negative ion examples from model 1
Number of protons – number of electrons = charge

48. Ga 3+
Br - 38 16 31 88 32 80 38 16 35 36 18 50 16 39
cation
anion
cation
anion
8. Could a +3 ion of aluminum be made by adding three protons to an aluminum atom?
No, changing the number of protons would change it into a different element
9. “When you add an electron, you get a positive charge because adding is positive in math.”
a. Explain why this student is incorrect
When you add an electron, you get a negatively charged ion.
b. Provide a better description of how math relates to electrons and ion formation
The electron has a negative charge, so you are adding a negative number

49. anions
cations
hydrogen

50. Physical Changes
Boil, melt, cut, break, split, grind, crush, bend, condense, freeze, dissolve and crack are examples of physical changes.
Physical change alters the substance without changing its composition or chemical identity.

51. Physical Properties
A physical property is a condition that can be measured or observed without changing the identity of the substance.
Examples of physical properties include color, solubility, odor, hardness, density, melting point and boiling point, etc.

52. Chemical Properties
The ability of a substance to undergo a chemical reaction to form a new substance is called a chemical property. Chemical properties are observed when a substance undergoes a chemical change.

53. Chemical Change
A change in which one or more substances are converted into different substances is called a chemical change or chemical reaction.
C + O2 CO2
(reactants) (product)

54. Look for terms such as . . . Combustion – powering the space shuttle
burn
rot
rust
decompose
ferment
explode
oxidize
corrode
grow
precipitate
gas formation
digest
Combustion – powering the space shuttle

55. Physical Change in Solids
The Chemistry of Solubility
Dissolving NaCl
Review solutions – solute vs solvent

57. Investigation 2: Physical properties and physical change in solids
Key concepts for students
● Solubility is a characteristic property of a substance.
● To measure equal amounts of different solids for a solubility test, it is better to use mass than volume.
● When comparing solubilities of different solids, all variables should be kept the same except for the
type of solid used.
● The way a substance recrystallizes is a characteristic property of that substance.
● Solubility and recrystallization can be used to help identify an unknown substance.
Learning objectives
Students will be able to:
● Develop an understanding of the meaning of characteristic properties of substances by testing
and comparing different household crystals.
● Recognize that solubility is a characteristic property of a substance.
● Identify an unknown crystal by comparing its characteristic physical properties with those of
four known crystals.
● Measure equal amounts of crystals by mass rather than volume.
● Identify possible variables and suggest ways to control them as they help design valid scientific
investigations.

58. Investigation 2: Physical properties and physical change in solids
Investigation questions
How can you tell if crystals that look the same are really the same or different?
Can you identify an unknown crystal by comparing its appearance to other known crystals?
Can you identify the unknown crystal by crushing the different crystals and comparing them?
Do some of the crystals dissolve more or less than others?
What is the best way to measure equal amounts of crystals?
Can you identify the unknown crystal by the amount that dissolves in water?
Can you identify the unknown crystal by the way it looks when it recrystallizes?

59. Physical Change in Solids - Summary
Physical change is a change that alters the form or appearance of a material without changing the chemical composition. One example of a physical change is dissolving.
Salt is made of ions that are ionically bonded together in a crystal.
Sugar is made of molecules that are bonded together based on the positively and negatively charged areas.
The positive and negative areas of water molecules are attracted to the oppositely charged ions in salt and to the positive and negative areas on sugar molecules.
Because salt and sugar are made up of different atoms that bond together differently, water is attracted to them differently. Water interacts and dissolves salt and sugar in characteristic ways
That’s why solids that may look similar behave differently.

60. Physical Properties and Physical Change in Liquids

62. Investigation 3: Physical properties and physical change in liquids
Key concepts for students
●Different liquids have different characteristic properties
● A solution made from water and another substance will have characteristics based on the interaction
between water and the other substance.
● The way a liquid behaves on a surface depends on the characteristics of the liquid and the characteristics of the surface.
● The way a liquid combines with water depends on the characteristics of the liquid and the characteristics of water.
Learning objectives
● Recognize that different liquids have unique characteristic properties.
● Identify and control variables as they design and conduct tests on each of the liquids.
● Identify unknown liquids based on the results of their tests.
● Understand that the way liquids behave on a surface has to do with the interaction between the
characteristics of the liquid and the characteristics of the surface.
● Understand that the way liquids combine with water has to do with the interaction between the
characteristics of the liquid and the characteristics of water.

63. Investigation 3: Physical properties and physical change in liquids
Investigation questions
How can you tell if liquids that look the same are really the same or different?
● Can you distinguish between four clear colorless liquids based on the way they look on a brown paper towel?
● How can you identify an unknown liquid based on the way it behaves on different paper surfaces?
● Can you tell a difference between liquids by the way they look when they combine with water?
● How can you use the characteristic way each liquid combines with water to identify the unknown liquids?

64. Solubility POGIL
Dissolving Solids, Liquids and Gases

66. Investigation 4: Dissolving Solids, Liquids and Gases
Key concepts for students
● Dissolving applies to solids, liquids, and gases.
● Dissolving involves the interaction between the solvent and the solute.
● The extent to which a substance dissolves in a liquid is a characteristic property of that substance.
● Heat increases the solubility of most solids.
● Heat does not increase the solubility of all solids by the same amount.
● Heat decreases the solubility of most gases.
Learning objectives
Students will be able to:
● Identify and control variables to design and conduct valid experiments.
● Develop a definition of “dissolve” that applies to solids, liquids, and gases.
● Use observations and results of experiments to develop explanations to answer a question.
● Explain that the solubility of a substance depends on the characteristics of both the solute and the
solvent giving each substance a unique solubility.
● Draw pictures and write captions showing the stages of a solid dissolving.
● Explain that heat affects the solubility of solids and gases differently.

67. Investigation 4: Dissolving Solids, Liquids and Gases
Investigation questions
Can solids, liquids, and gases all dissolve?
● How can you tell when a substance is dissolved?
● Does colored sugar dissolve equally well in water, vegetable oil, and alcohol?
● Does cocoa mix dissolve better in hot water or cold water?
● Do salt and sugar dissolve better in hot water than in cold water?
● Do all liquids dissolve in water?
● Can a gas dissolve in a liquid?
● Does temperature have an effect on how quickly dissolved gas escapes from a soda?
● How can you make a lemon soda that keeps as much carbonation as possible?

68. Dissolving - Summary Solids, liquids, and gases can all dissolve.
Dissolving depends on the molecules of the substance doing the dissolving,
called the solvent, and the molecules of the substance being dissolved,
called the solute.
Dissolving is the process in which these molecules interact and attract each
other to form a solution.
The extent to which a substance dissolves is a characteristic property of that
substance called its solubility.
Water is a good dissolver because of its areas of positive and negative
charge. The mutual attraction between water molecules and other
substances with positive and negative charges causes these substances to
dissolve.

69. Chemical Change
Acid/Base POGIL
Calculating pH POGIL

70. A substance that releases H+ ions in an aqueous solution
Acid:
A substance that releases H+ ions in an aqueous solution
“aqueous” means: water

71. H Characteristics of Acids: Acids have a sour taste
Acids react with metals
Acids contain Hydrogen
Many are poisonous and corrosive to skin H

72. Strong Acids
(break down completely to give off many H+ ions)

73. Weak Acids
(only partially breaks down, gives less H+)

74. Acids and Bases Acids: Some common acids in our daily life:
Ethanoic Acid, CH3COOH: found in vinegar, tomato juice
Citric Acid, C6H8O7: found in citrus fruits
Lactic Acid: found in sour milk, yogurt
Tannic Acid: Found in tea
Tartaric Acid: Found in grapes
What about those commonly found in our lab?
Hydrochloric acid, HCl
Sulfuric Acid, H2SO4
Nitric Acid, HNO3
Which of these is found in batteries?
Sulfuric Acid

75. Base:
A substance that releases OH- ions in an aqueous solution

76. OH- Characteristics of Bases: Bases usually taste bitter
Bases feel slippery
Bases contain hydroxide ions
STRONG bases are also poisonous and corrosive to skin
OH-

77. (Hydroxides of Group 1 and Group 2 Metals are STRONG)
Common Bases:
Strong Bases
The Formulae
Lithium hydroxide
Sodium hydroxide
Potassium hydroxide
Rubidium hydroxide
Caesium hydroxide
Barium hydroxide
Calcium hydroxide
Strontium hydroxide
LiOH
NaOH
KOH
RbOH
CsOH
Ba(OH)2
Ca(OH)2
Sr(OH)2
(Hydroxides of Group 1 and Group 2 Metals are STRONG)
All others are WEAK

78. Some bases (VERY FEW)
don’t have OH-
Most commonly:
ammonia NH3

79. Reactions between acids and bases
When and acid and a base react with each other, the characteristic properties of both are destroyed. This is called neutralization.

80. Reactions between acids and bases
General formula for acid base reaction:
Acid +
Base →
Salt
H2O +
NOT JUST
NaCl !!
“Salt” means any ionic compound formed from an acid/base reaction
Neutralization Reaction Animation

81. Neutralization
HCl + NaOH → H2O + NaCl
acid base water salt

82. Neutralization HNO3 + KOH → H2O + KNO3 H NO3 K OH Another Example
acid base water salt

83. Indicators
An indicator is a compound that will change color in the presence of an acid or base
Red Litmus-Turns blue in base
Blue Litmus-Turns red in acid
Universal indicator (pH paper) Used for the full pH range
Phenolphthalein-Turns pink in base

84. pH
pH stands for “potential hydrogen” and is a measure of how many H+ ions there are in solution.
The MORE H+ there are, the LOWER the pH will be.
pH = - log [H+]

85. Shows the range of H+ concentrations
pH Scale
Shows the range of H+ concentrations
High H+ concentration
Low H+ concentration
Virtual demonstration - Detecting acid/base

87. Investigation 5: Chemical Change
Key concepts for students
● Substances react chemically in characteristic ways.
● Evidence that a chemical reaction has occurred includes: production of a gas, change in temperature,
color change, and formation of a precipitate.
● A chemical reaction can be controlled by adjusting the amount of reactants.
● A chemical reaction can result in an increase in temperature (exothermic) or a decrease in
temperature (endothermic).
● The color change of an acid–base indicator can help classify a solution as an acid or a base, identify
when a solution has been neutralized, and compare the amount of acid or base in a solution.
● In a chemical reaction, the bonds holding one atom to another are broken, atoms rearrange, and
then combine in new ways to create one or more different substances.
● In a chemical reaction, the atoms that make up the reactants are never destroyed or disappear. They
rearrange and bond in new ways to form the products.
Learning objectives
Students will be able to:
● Design a testing procedure to compare the chemical reactions of different substances.
● Use the characteristic chemical reactions to identify an unknown substance.
● Recognize that production of a gas, change in temperature, color change, and formation of a precipitate
are evidence of chemical change.
● Use a thermometer and graduated cylinder accurately.
● Control chemical reactions by adjusting the amount of the reactants.
● Use the color changes of an acid-base indicator to classify and compare different substances.
● Determine whether a new substance is created during a chemical reaction.

88. Investigation 5: Chemical Change
Investigation questions
● Do powders that look the same have the same chemical reactions?
● How can you use the characteristic ways substances react to tell similar-looking substances apart?
● How can you identify an unknown powder?
● What are the active ingredients in baking powder?
● Aside from bubbling, what else happens during a reaction between baking soda and vinegar?
● How can you control the amount of gas produced in a baking soda-and-vinegar reaction?
● Can the temperature increase during a chemical reaction?
● How can you tell if a substance is an acid, a base, or neutral?
● How can you return the color of a red cabbage indicator solution back to blue?
● How can neutralizing acids help you compare the amount of acid in different solutions?
● What happens when soap is added to hard water?

89. Relevant National Science Education Standards:
K–4
Physical science
Properties of objects and materials
Objects have many observable properties
Science as inquiry
Abilities necessary to do scientific inquiry
Ask a question about objects.
Plan and conduct a simple investigation.
Use simple equipment and tools to gather
and extend the senses.
Use data to construct a reasonable
explanation.
Communicate investigations and
explanations.
Understandings about scientific inquiry
Scientific investigations involve asking and
answering a question.
Types of investigations include describing
objects…and doing a fair test.
Good explanations are based on evidence
from investigations
5-8
Physical science
Properties and changes of properties in matter
A substance has characteristic properties
Science as inquiry
Abilities necessary to do scientific inquiry
Identify questions that can be answered through
scientific investigations.
Design and conduct a scientific investigation.
Use appropriate tools and techniques to gather,
analyze, and interpret data.
Develop descriptions, explanations, predictions, and
models using evidence.
Think critically and logically to make the relationships
between evidence and explanations.
Communicate scientific procedures and explanations.
Understandings about scientific inquiry
Different kinds of questions suggest different kinds of
Scientific explanations emphasize evidence and have
logically consistent arguments.
Scientific investigations sometimes result in new
ideas and phenomena for study that can lead to
new investigations.

90. Chemical Change - Summary
A chemical reaction happens when one or more substances change into entirely new substances with different properties.
The clues of a chemical reaction are production of a gas, change in temperature, color change, production of a precipitate.
In a chemical reaction, it takes energy to break the bonds in the reactants and energy is released when bonds are formed in the products.
If more energy is required to break the bonds than is released when new bonds are formed, the reaction is endothermic.