Welcome !!!!

• Dr. Leslie Sombers leslie_sombers@ncsu.edu

• Lingjiao Qi lqi@ncsu.edu

http://moodle.wolfware.ncsu.edu

In the top left, click Guest Login --> Create new account.

www.saplinglearning.com

In the top right, click orange button ‘register here’.

Click the link in the email when it arrives. Under ‘search courses’, type in ‘Lee County - 2013’.

Enter 51912 as the key code.

Copyright © Houghton Mifflin Company.All rights reserved.

Presentation of Lecture Outlines, 2–2

Go to http://saplinglearning.com2a. If you already have a Sapling Learning account, log in then skip to step 3.2b. If you have Facebook account, you can use it to quickly create a SaplingLearning account. Click the blue button with the Facebook symbol on it (just to the left of the username field). The form will auto-fill with information from your Facebook account (you may need to log into Facebook in the popup window first). Choose a password and timezone, accept the site policy agreement, and click "Create my new account". You can then skip to step 3. 2c. Otherwise, click "Create Account". Supply the requested information and click "Create my new account". Check your email (and spam filter) for a message from Sapling Learning and click on the link provided in that email.3. Find your course in the list (you may need to expand the subject and term categories, NC State – Summer 13) and click the link.4. Enter 51912 as the key code.

Logging into Sapling….

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.

Your assignment:

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!

Copyright © Houghton Mifflin Company.All rights reserved.

Presentation of Lecture Outlines, 2–5

Pre- test

To assess content knowledge and learning…..Sorry guys, it’s a requirement!!!!

Some Definitions….

• Hypothesis:

• Theory:

• Variable:

• Fact:

• Law:

a proposed explanation for a phenomenon. Generally based on observations

a value that may change within the scope of a given problem

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.

Hypothesis that has been tested over long periods

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.

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.

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.

Elements and CompoundsAn 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….

Extensive vs. IntensiveExtensive 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.

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

Metric System

• 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

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

https://www.youtube.com/watch?v=IhtgKHYZti0

Metric System

• 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 = 16093 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 = 16.093 kilometers (or 16.1 if rounded to 1 decimal place)

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

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Metric System

– Centimeters are 10 times larger than millimeters so it takes more millimeters for the same length

1 centimeter = 10 millimetersExample not to scale

1 mm

1 mm

1 mm

1 mm

1 mm

1 mm

1 mm

1 mm

1 mm

1 mm

1 cm

40

41

41

40

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

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

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 centimetersor

1.00 meter = 10.0 decimeters = 100. centimeters

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Metric System• Now let’s try our previous example from meters to

kilometers:16093 meters = 1609.3 decameters = 160.93

hectometers = 16.093 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

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

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

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Metric System• Now let’s start from centimeters and convert to

kilometers

400000 centimeters = ? kilometers

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Kilo(1000)

Hecto(100)

Deca(10)

Base Units

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Metric System• Now let’s start from meters and convert to centimeters

5 meters = ? centimeters

• Now let’s start from kilometers and convert to meters

.3 kilometers = ? meters

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

metergramliter

deci(1/10)

centi(1/100)

milli(1/1000)

Copyright © Houghton Mifflin Company.All rights reserved.

Presentation of Lecture Outlines, 2–24

Standard Metric Prefixes for the SI Units

Matter POGIL

http://preparatorychemistry.com/KMT_flash.htmThe structure of matter

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

ACS – Inquiry in Action. A guided-inquiry approach.

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.

Goal: students will acquire both the skills of scientific inquiry and the concepts of the physical science curriculum

Essential Features of Inquiry:

1. Students begin with a question that can be answered in a scientific way2. Students rely on evidence in attempting to answer the question3. Students form an explanation to answer the question based on the evidence collected4. Students evaluate their explanation

Science as inquiry: Abilities necessary to do scientific inquiry

Science as inquiry: Understandings about scientific inquiry

Physical science content standards

Question to investigateA question at the beginning of each activity serves as a guide for designing and conductingthe experiments to answer that question. All the activities within an investigationlead up to or contribute to the overall objective of the investigation.ProcedureProcedures are examples or models of ways to design and conduct anexperiment to answer the question to investigate. Because student input in the experimentaldesign 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 resultsThe expected results describe what would happen if the activities wereconducted exactly as written. These should be used as a guide, as the procedures studentsdevelop may vary.Activity sheetsEach activity has a corresponding activity sheet, which guides students as they conductthe activity. The activity sheets help students plan their experiments, recordtheir observations, draw conclusions based on observations, offer explanations, andapply their learning. When needed, the activity sheets also contain science content.AssessmentOne scoring rubric is included with each investigation. This can be used as a formativeassessment of the students’ work on the activity sheets and their performancedoing the hands-on activities that were a part of the investigation. A separate summativeassessment for the investigation, called Review and apply, is included at theend of each investigation.

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.

O

H H

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

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.

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 makesthe area around the oxygen atom slightly negatively charged. It also leaves thearea around the hydrogen atoms slightly positively charged.

O

H H

OHH

- -

+ +BEFORE AFTER

A picture of water

- -

+ +The charge density model

O

H H

OH H

+ +

- -

The space-filling model

O

H H

The ball and stick model

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

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)

Dissolution – 2 sucrose molecules dissolving in water

1 2

3 4

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 objectivesStudents 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.

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?

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.

http://preparatorychemistry.com/water_flash.htmThe structure of water

Review - How are ions made from neutral atoms?

Yes Yes no

metalmetal

nonmetal

nonmetal

Yes

YesYes

Yes Yes

Yes

Yes

Yes nono

no

Ion POGIL

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?

5. Which subatomic particle carries a negative charge?

protons

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

38

88

38

36

50

cation

16

32

16

18

16

anion

70 31 Ga 3+

31

39

cation anion

80 35 Br -

80

35

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

anions

cations

hydrogen

Physical Changes• Physical

change alters the substance without changing its composition or chemical identity.

• Boil, melt, cut, break, split, grind, crush, bend, condense, freeze, dissolve and crack are examples of physical changes.

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.

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.

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)

Look for terms such as . . .

• burn • rot• rust• decompose • ferment • explode • oxidize • corrode • grow • precipitate• gas formation• digest

Combustion – powering the space shuttle

Physical Change in Solids

http://www.inquiryinaction.org/chemistryreview/solids/The Chemistry of Solubility

Dissolving NaCl

http://preparatorychemistry.com/NaCl_flash.htm

Review solutions – solute vs solvent

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.

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?

Investigation 2: Physical properties and physical change in solids

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.

Physical Properties and Physical Change in Liquids

http://www.inquiryinaction.org/chemistryreview/liquids/

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.

Investigation questionsHow 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?

Investigation 3: Physical properties and physical change in liquids

Dissolving Solids, Liquids and Gases

http://www.inquiryinaction.org/chemistryreview/dissolving/

Solubility POGIL

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 objectivesStudents 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.

Investigation questionsCan 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?

Investigation 4: Dissolving Solids, Liquids and Gases

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.

Chemical Change

http://www.inquiryinaction.org/chemistryreview/chemical_change/

Acid/Base POGIL

Calculating pH POGIL

Acid:

A substance that releases H+ ions in an aqueous solution

“aqueous” means: water

Characteristics of Acids:

Acids have a sour taste Acids react with metals

Acids contain Hydrogen

Many are poisonous and corrosive to skin

H

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

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

Acids and BasesAcids:

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, HNO3Which of these is found in batteries? Sulfuric Acid

Base:

A substance that releases OH- ions in an aqueous solution

Characteristics of Bases:

Bases usually taste bitter Bases feel slippery Bases contain hydroxide ions STRONG bases are also poisonous and corrosive to skin

OH-

Strong Bases The Formulae

Lithium hydroxideSodium hydroxidePotassium hydroxideRubidium hydroxideCaesium hydroxideBarium hydroxideCalcium hydroxideStrontium hydroxide

LiOHNaOHKOHRbOHCsOHBa(OH)2

Ca(OH)2

Sr(OH)2

Common Bases:

(Hydroxides of Group 1 and Group 2 Metals are STRONG)

All others are WEAK

Some bases (VERY FEW) don’t have OH-

Most commonly: ammonia NH3

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.

Reactions between acids and bases

General formula for acid base reaction:

Acid + Base → H2O +Salt

“Salt” means any ionic compound formed from an acid/base reaction

NOT JUST NaCl !!

Neutralization Reaction Animation

Neutralization

HCl + NaOH → H2O + NaCl acid base water salt

NeutralizationAnother Example

HNO3 + KOH → H2O + KNO3

H OHKNO3

acid base water salt

IndicatorsAn indicator is a compound that will change color in the presence of an acid or base

Universal indicator (pH paper) Used for the full pH range

Red Litmus-Turns blue in baseBlue Litmus-Turns red in acid

Phenolphthalein-Turns pink in base

pHpH 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+]

pH ScaleShows the range of H+

concentrations

High H+ concentration Low H+ concentration

Virtual demonstration - Detecting acid/base

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 objectivesStudents 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.

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?

Investigation 5: Chemical Change

Relevant National Science Education Standards:

K–4Physical 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

5-8Physical science

Properties and changes of properties in matter A substance has characteristic properties

Science as inquiryAbilities 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 investigations. 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.

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.