Handbook c1 states of matter and elements, compounds, and mixtures1

Agastya International Foundation

States of Matter and Elements, Compounds, Mixtures Handbook C1

“Every great and deep difficulty bears in itself its own solution. It forces us to change our thinking in order to find it.�

-Neils Bohr (1885-1962)

2

Handbook C1 States of Matter and Elements, Compounds, Mixtures OVERVIEW OF HANDBOOK S.No

Concept

No. Of Activities

Time (min)

Page No

1

What is matter? Properties of matter.

5

60

2

2

Physical and Chemical Changes (OPTIONAL)

5

50

13

3

Matter can change from one state to another

4

65

21

4

Introduction to Elements, compounds and mixtures

6

60

34

Total Time

235mins

Note: Elements, Compounds, Mixtures has been included in this handbook for convenience and because it uses many fundamentals from States of Matter.

ABL WITH REFERENCE TO STANDARD S. No

STANDARD

RELEVANT ABL

1

6

ABL 1

2

6

ABL 2

3

6

ABL 3

4

7 and 8

ABL 4

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LIST OF FIGURES, CHARTS AND WORKSHEETS S.No

Name

Page Number

Chart 1

Changes in States of Matter

23

Fig 1

Melting of Ice

26

Fig 2

Boiling Point of Water

28

Fig 3

Sublimation of Iodine

30

Fig 4

Classification of matter

49

Worksheet 1

Observation Sheet- 1 (Elements and compounds)

40

Worksheet 2

Large copy of observation sheet -1 (Elements and compounds)

40

Worksheet 3

Large copy of observation sheet (mixtures) -2

44

Note to Instructor: All the figures in this handbook are for the instructor’s reference only. The Charts need to be printed and shown to the students during the course of the activity. Worksheets need to be printed out in advance for the students. The number of worksheets required is mentioned in the Material List.

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ABL 1 Matter Around Us ABL

Learning Objective

1.1

What is matter?

  

Everything around is matter.

Matter has mass and occupies space.

All matter is made up of tiny particles called Atoms.

25

1.2

How do particles in matter behave?



The particles in matter are attracted to one another, but they have space between them.

They are constantly moving. Forces of attraction keep the particles close together.

15

What are the different states of matter?



Matter is found in three states- solid, liquid and gaseous.

Solids have a fixed shape, structure and volume.

The particles in a solid have no space between them to move, and are tightly packed.

Liquids take the shape of the container they are in, but have a constant volume. The particles in a liquid are close together, but they are free to move.

Gases have no fixed shape or volume. The particles in gases are very far from each other and are completely free to move around.

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Physical change is a temporary change with a change in appearance. No new substance is formed.

Chemical change is usually a permanent change, with a change in composition. One or more new substances are formed

5

1.3

Key Messages









1.4

Evaluation on Physical and Chemical Changes





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Time

65 min

5

ABL 1.1

Time: 10 min

LEARNING OBJECTIVE: What is matter?

ADVANCE PREPARATION: Material List: Not Applicable Things to Do: Not Applicable Safety Precautions: Not Applicable

SESSION Link to known information/previous activity: We are surrounded by things and objects, but what are they all made of? Let’s find out.

Procedure:

Begin the lesson by asking learners if they know what matter is. Let them attempt to define matter in their own words. After the class has attempted to answer, explain the following: Matter is everything around us. Everything we see around us, touch, use, eat, is matter. Matter can be described as anything that takes up space and has mass. The books in front of you, the blackboard, even you and me, are matter!

Now ask the class if they can name a substance that is not Matter. Wait for their responses. Many students might say ‘air’ or ‘smoke’. Explain that even air has a certain mass and it does occupy space, hence it is matter. Everything you can think of in our surroundings is matter!

UNDERSTANDING THE ACTIVITY: Leading questions: 1. What is matter made up of?

2. Why do we say that air is also matter?

3. Can you prove that air also consists of matter?

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Discussion and Explanation: 1. We have now learnt that everything around us is matter, and that matter occupies space and has mass.

All matter is made up of tiny particles called atoms. So, everything we see is made up of atoms.

2. The air that we breathe is made up of millions and millions of particles of oxygen, carbon dioxide, nitrogen, and other gases. Even though we can’t see air, it still has a small mass, and it still occupies space. This is why air is also matter.

3. There are many experiments to show that air occupies space. In the next activity, we will learn an easy way to demonstrate it.

KEY MESSAGES:   

Everything around us is matter.

Matter has mass and occupies space.

All matter is made up of tiny particles called Atoms.

Time: 15 min

ABL 1.1 b LEARNING OBJECTIVE: Does air occupy space?

ADVANCE PREPARATION: Material List: S.No

Material

Quantity

1

Glass Trough or Plastic Tub

1 per class

2

Test Tube

1 or 2 per class

3

Water

Enough to fill the trough.

Things to Do: Fill a trough with water before the class begins, and place it in such a way that all the learners are able to see it clearly.

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SESSION Link to known information/ previous activity: We have learnt that air is also matter. Let us try to demonstrate this further.

Procedure: - Fill the trough with water up till the brim.

-Take a test tube with a wide mouth. Take a sheet of paper and crumple it into a ball.

- Stuff the ball of paper into the test tube. Make sure the paper is right at the bottomof the test tube.

- Invert the test tube and put it into the trough or tub of water. Make the mouth of the test tube touch the bottom of the tub.

- Make sure that you put the test tube straight into the tub. Do not tilt the test tube while immersing it in water.

- Make all the learners come up to the table to take a look at the test tube.

- Now slowly remove the test tube, making sure you do not tilt it while removing.

- Take out the ball of paper from the tube and ask learners to inspect it.

UNDERSTANDING THE ACTIVITY: Leading Questions: 1. Did the ball of paper get wet?

2. How did the paper manage to remain dry despite immersing the test tube in water?

Discussion and Explanation: 1. When the ball of paper is removed from the test tube, we find that it is still dry.

2. There is air in the test tube above the paper. When we insert the test tube into the tub of water, the air does not escape completely. There is still a small amount of air left in the test tube.

The leftover air occupies the small gap between the paper and the water, thereby preventing the paper from getting wet.

KEY MESSAGES: 

Air occupies space.

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Note to Instructor: Agastya Manual 1, Experiment 1, is another demonstration to show that air occupies space.

LEARNING CHECK: Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

Time: 15 min

ABL 1.2 LEARNING OBJECTIVE: How do particles in matter behave?

ADVANCE PREPARATION: Material List: S.no

Material

Quantity

1

Glass beakers (250ml)

4 per class

2

Marbles

1 bag

3

Salt

One tablespoon

4

Potassium permanganate

1 crystal

5

Water

To fill all the beakers

6

Dropper

1 per class

7

Glass rod

1 per class

8

3KG cardboard placards

1 set per class

(on the first card write SOLIDS, on the second LIQUIDS, and the third GASES)

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Not Applicable Safety Precautions: Not Applicable

SESSION 1.2 A Link to known information/previous activity: Now that we have learnt what matter is made up of, let us understand the behavior of the particles in matter.

Procedure: This activity is a demo.Fill the first beaker with water up till the brim. Ask one of the learners to volunteer to perform this activity. Tell the volunteer to add a tablespoon of salt into the water in the first beaker, slowly.

Before the volunteer pours the salt into the water, ask the class whether the water will overflow or not.

Make sure you add the salt VERY slowly to the beaker.

Now fill the second beaker completely with marbles. There is no water in this beaker. Ask learners what will happen if you add salt to this beaker. Ask the volunteer to add salt to this second beaker, and the other learners to watch closely.

UNDERSTANDING THE ACTIVITY: Leading Questions: 1. What happened when we added salt to the first beaker?

2. What happened when we put salt in the beaker containing marbles?

3. Why did the water not overflow from the first beaker when we added salt to it?

Discussion and Explanation: 1. When we add salt to the first beaker containing water, the water in the beaker does not overflow, even though the beaker is filled up till the brim.

2. When we add salt to the beaker containing marbles, the salt goes through the spaces between the marbles, and reaches the bottom of the beaker.

3. Imagine the marbles to be water molecules. The marbles help us understand that there are spaces between the molecules in water, and this is where the salt particles are placed. This is why the water did not overflow from the first beaker. The salt molecules settle in the spaces between the water molecules, so even though the water was filled up till the brim, there was still some space left for the salt particles. This space is referred to as inter-molecular space.

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SESSION 1.2 B Procedure: -Fill all the four beakers with 200 ml of water.

-Add one crystal of potassium permanganate into the first beaker. Wait until the crystal has completely dissolved and the water is uniformly colored. Ask the class to observe what happens.

This should not take longer than five minutes, but if the water has not reached a uniform color after five minutes, stir it with the glass rod. Only the first beaker can be stirred, make sure you do not stir any of the other beakers.

-Now take some of this solution in a drop and add exactly 10 drops to the second beaker.

-Similarly take some solution from the second beaker in the dropper, and add to the 10 drops to the third.

Take 10 drops from the third beaker and add it to the fourth one.

-Do not shake or stir any of the beakers. Wait patiently until the water is uniformly colored.

UNDERSTANDING THE ACTIVITY: Leading questions: 1. What happens to thewater in thefirst beaker when we add the crystal of potassium permanganate?

2. What happens to the second, third and fourth beakers?

3. Why does the color change in the beakers?

Discussion and Explanation: 1. When we add the crystal of potassium permanganate to the first beaker, the water in it slowly starts to change color. In some time, the water has a purplish-pink color to it.

2. When we add a small amount of this solution to the second beaker, the color in it changes. Similarly the third and fourth beaker also show some color. However, the intensity of the color has reduced as we go from the first beaker to the fourth.

3. The color in the beakers changes because of particles of potassium permanganate in the water. The particles of potassium permanganate are moving constantly, which is why the solution gets uniformly colored. In the fourth beaker, we added such a small quantity of potassium permanganate, yet the water in the beaker changed color. Imagine how small the particles must be, if even a tiny amount of Agastya International Foundation. For Internal Circulation only.

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the chemical can color all the water in the beaker! These particles are also attracted to each other, and there are forces holding them close to each other.

KEY MESSAGES:  

The particles in matter are attracted to one another, but they have space between them.

They are constantly moving. Forces of attraction keep the particles close together.

LEARNING CHECK: Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

ABL 1.3

Time: 20 min

LEARNING OBJECTIVE: What are the different states of matter?

ADVANCE PREPARATION: Material List: A few pieces of chalk Things to Do: Clear a portion of the room and draw three 4ftX4ft boxes on the floor. Number the boxes 1, 2, and 3.

SESSION Link to known information/previous activity: We have learnt that matter occupies space and consists of particles called atoms. Now let us see if all matter looks and behaves in the same way.

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Procedure: Ask the class to give you some common examples of solids, liquids and gases. Some likely answers are: Solids- wall, benches, bags, books, blackboard.

Liquids- water, milk, petrol, tea, oil, honey.

Gases-air, steam, agarbati smoke.

Write the answers down in 3 columns on the board. Ask the learners to note that all the objects named occupy space and have mass. Therefore they are all “Matter”. So we can say that matter can exist in 3 statesSolid, Liquid and Gas. These are known as the three “States of Matter” Now tell learners that they will learn more about the particles in matter in the three different states. Pick 1012 learners and make them stand in box number one .Pick as many learners as you need to pack the box tightly. The learners in this box must be packed so tightly that there’s no room for them to move. Tell them that they must stand within the four boundaries of the box for the activity, and that they must not move. The students must hold hands within the box, and must not move around.

Now choose 5-6 learners to stand in box number 2. Learners in box number two also must hold hands, but they have space to move around. Tell them that they are free to move within the box but not outside it.

Now pick 3 learners and make them stand in box number 3. They are allowed to move as freely as they can within the box.

After about 1 minute, hold up the placards with SOLID, LIQUID and GAS, one by one. Ask the groups to choose one for each group.

UNDERSTANDING THE ACTIVITY: Leading questions:

1. What placard did you choose? What do the students in the boxes represent?

2. You chose one “name” for your group. How do you think particles move in that state of matter?

Discussion and Explanation: 1. Students in box number 1 choose SOLIDS, number 2 choose LIQUID and number 3 choose GAS. Note to Instructor: In case the learners choose the wrong placard, please correct them.

The students in the boxes are like the particles in different states of matter-solid, liquid and gas.

2. Box number 1 is like a solid. The particles are packed together very tightly, and in a fixed arrangement. There is no room for movement of particles. Solids have a fixed structure, and their shape and volume does not change.

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Box number 2 is like a liquid. The particles are close together but not in a fixed arrangement. The particles have space to move. Liquids have no fixed shape, they take the shape of the container, but their volume remains the same.

Box number 3 is like a gas. In gases, the particles are separate, and very far from each other. There is a lot of space for particles to move around freely, and this is why gases have no fixed volume or shape.

Now let us look back at back at the solids, liquids and gases that we see in our everyday life.

Note to Instructor: Now go back to the list you have written on the board of solids, liquids and gases.

KEY MESSAGES:    

Matter is found in three states- solid, liquid and gaseous.

Solids have a fixed shape, structure and volume. The particles in a solid have no space between them to move, they are tightly packed.

Liquids take the shape of the container they are in, but have a constant volume. The particles in a liquid are close together, but they are free to move.

Gases have no fixed shape or volume. The particles in gases are very far from each other and are completely free to move around.

LEARNING CHECK: Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

WEB RESOURCES: http://phet.colorado.edu/en/simulation/states-of-matter-basics

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ABL 1.4

Time: 5 min

Note to Instructor: This ABL is to evaluate how comfortable your class is with physical and chemical changes.

In case most of the students are not able to answer the questions or are answering incorrectly, it would be advisable to do the entire ABL on Physical and Chemical Changes, which is ABL 3 at the end of the handbook.

If the learners perform well and are well versed with the topic, there is no need to do ABL 3. Please treat ABL 3 as an optional ABL, depending upon the performance of your class on this ABL.

LEARNING OBJECTIVE: What are Physical and Chemical Changes?

ADVANCE PREPARATION: Material List: Not Applicable Things to do: Not Applicable Safety Precautions: Not Applicable Procedure: Ask your class whether the following reactions are Physical or Chemical Changes. Also ask them to explain the reason behind their answer.

1. Burning of Paper Answer for Instructor’s Reference: Burning of paper is a chemical change because paper burns in the presence of oxygen to become a different substance, it is no longer paper; it burns to form ash.

2. Milk turning sour (Curdling of Milk).

Answer for Instructor’s Reference: When milk turns sour, the lactose (primary carbohydrate in milk), turns into lactic acid. This is why it is a chemical change.

3. Cutting potatoes into small pieces.

Answer for Instructor’s Reference: Cutting potatoes is a physical change. The potatoes do not change form when they are cut, only their appearance is changed.

4. A big piece of wood being sawed into two.

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Answer for Instructor’s Reference: Sawing a piece of wood into two pieces is a physical change. Only the appearance of wood changes, but there is no difference in its composition.

5. Formation of Bubbles while boiling water.

Answer for Instructor’s Reference: Formation of bubbles while boiling water is a physical change. Only the appearance of the water changes, its composition is not altered.

6. ‘Fizzing’ of aerated drinks.

Answer for Instructor’s Reference: You must have noticed the formation of numerous tiny gas bubbles when you open a bottle of any aerated drink like soda, pepsi, coke, etc. This is a physical change. The carbon dioxide that is dissolved in the drink comes out as bubbles or fizz. There is no change in composition.

7. Rising of Idli Batter.

Answer for Instructor’s Reference: The rising of idli batter is a chemical change. This is because the batter ferments and carbon dioxide is released, which causes the batter to rise.

8. Dissolving sugar in water.

Answer for Instructor’s Reference: Dissolving sugar in water is a physical change. This is because once you evaporate the water, you can get back the sugar.

9. Boiling milk.

Answer for Instructor’s Reference: Boiling of milk is a physical change. The milk only changes in appearance; its composition remains the same.

10. Breaking of glass.

Answer for Instructor’s Reference: A glass breaking is a physical change. Only the appearance of the glass changes, its chemical composition is still the same.

KEY MESSAGES:  

Physical change is a temporary change with a change in appearance. No new substance is formed.

Chemical change is usually a permanent change, with a change in composition. One or more new substances are formed.

LEARNING CHECK:

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Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

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ABL 2 Physical and Chemical Changes Note to Instructor: This entire ABL is OPTIONAL. Please do this ABL at the end of ABL 1 in case your students perform poorly in the evaluation (ABL 1.4). If learners perform well in the evaluation, there is no need to carry out the whole ABL. You can just refresh the learners’ memory by running through the Key Messages quickly. This ABL is taken from ABL 1 of the handbook on ‘Chemical Reactions’.

ABL

Learning Objective

2.1

What is a physical change?

2.2

What is a chemical change?

Key Messages 

Physical change is a temporary change  Physical properties of the substance are altered  No new substance is formed  Chemical change is usually a permanent change  Change in composition takes place  One or more new substances are formed Total Time

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Time (min) 15

35

50 min

18

ABL 2.1

Time: 15 min

LEARNING OBJECTIVE – What is a physical change?

Note to instructor – This activity shows that substances can be changed in many ways and introduces students to how we can identify a physical change.

ADVANCE PREPARATION: Material List S. No Material 1. A 5 g piece of candle wax

Quantity 1 per class

2. China dish

1 per class

3. Spirit lamp

1 per class

4. Tripod stand

1 per class

5. Wire gauze

1 per class

6. Tongs

1 per class

7. Matchbox

1 per class

Things to do Set up the tripod over the spirit lamp and place the wire gauze on the tripod. Place the wax in the china dish and place the china dish on the wire gauze. Place the experimental set up in a place where the students can observe from a safe distance.

Safety Precautions Tell the students that they should not touch any of the experimental materials

SESSION Link to known information/previous activity: Not Applicable

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Procedure Divide the class into groups of 4-5. Turn on the spirit lamp and gently heat the wax in the china dish. Use the tongs to hold the china dish while heating. Display the melted wax to the students and then set the china dish aside, away from the students, and allow it to cool. Show this to the students after a few minutes, when the wax starts becoming solid again.

UNDERSTANDING THE ACTIVITY Leading questions 1 1. What does the piece of wax look like?

2. What happened when we heated the wax?

3. What happened when we cooled the wax?

4. Were the physical properties of the cooled wax the same as the physical properties of the candle piece?

5. Was there any new substance formed after the wax was melted and then cooled?

6. What is such a change called?

7. Is a physical change reversible?

8. Can you give examples of some physical changes that you have come across in your daily life?

9. Cutting and tearing of a substance is not reversible, how is it a physical change?

10. How is drying of clothes a physical change?

11. How is stretching of a rubber band a physical change?

12. How is dissolving salt/sugar in water a physical change?

Discussion and Explanation 1. Wax looks white in color; it is solid and has the cylindrical shape of a candle.

2. When we heated the wax, it became liquid. It started to lose its shape and it became colorless.

3. When we cooled the wax, it again looked white and was solid. But its shape changed to the shape of the inside of the china dish.

4. The shape of the cooled wax was different from the shape of the original wax. All other physical properties were the same.

5. No new substance is formed; if the cooled wax in the china dish was formed into a candle, it would burn just like the original candle 6. A change in one or more of the following properties - the physical state, shape and color of a substance - is called a physical change.

7. On heating, the wax turned from solid to liquid. Again on cooling, it became solid again. A physical change is a temporary, reversible change.

8. Boiling of water, drying clothes, stretching a rubber band, tearing of paper, cutting of cloth, dissolving salt/sugar in water etc are examples of physical change.

9. Cutting and tearing result in the making the substance smaller – however, the substance remains the same.

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10. On drying clothes, water is lost in the form of water vapour. The cloth is still the same and water is in the form of water vapour.

11. Stretching a rubber band increases its size, but nothing happens to its internal composition. When you stop stretching the rubber band, it returns to its original shape and size.

12. Once salt (or sugar) is dissolved in water, it loses its physical state and crystalline shape. However, if the salt solution is evaporated,salt crystals are recovered.

KEY MESSAGES   

Physical change is a temporary change Physical properties of the substance are altered No new substance is formed

LEARNING CHECK Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

TRY IT YOURSELF Look for simple examples of physical changes in your daily life and discuss them with your teacher and classmates

ABL 2.2 LEARNING OBJECTIVE –What is a chemical change?

Note to instructor – Here we talk about chemical changes. Stress is given on the chemical combining or breaking down of substances. We will also be using the observations on the wax melting to compare physical and chemical changes.

ADVANCE PREPARATION Material List S.No 1.

Material 5g sulphur

Quantity 1 per class

2.

1 tsp sugar

1 per class

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3.

5cm magnesium strip

1 per class

4.

1 spatula

1 per class

5.

1 china dish

1 per class

6.

1 spirit lamp

1 per class

7.

1 tripod stand

1 per class

8.

1 wire gauze

1 per class

9.

1 spirit lamp

1 per class

10.

1 matchbox

1 per class

11.

Tongs/test tube holders

1 per class

12.

Deflagrating spoon

1 per class

13.

Gas jar

1 per class

14.

1 per class

15.

Hibiscus or any colored flower Beaker/glass cup

16.

Sandpaper

1 per class

17.

Spoon

1 per class

18.

1 pair of safety gloves

1 per class

19.

1 pair of safety goggles

1 per class

20.

Matchbox

1 per class

21.

Activity Cards

1 per group

1 per class

Chemical Reactions Activity Cards.docx

22.

Chemical Reactions – Observation Sheet -1

1 per learner

Chemical Reactions Observation Sheet 1.docx

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Things to do Set up the tripod over the spirit lamp and place the wire gauze on the tripod. Place the experimental set up in a place where the students can observe from a safe distance. Make sure to remove any salts/dust formed on the magnesium tape using sand paper. Print the activity cards for Procedure-4.

Safety Precautions Tell the students to keep a safe distance and not to touch any of the materials or apparatus used in the experiment.Ask them to not touch the molten wax or look directly at the burning magnesium strip.

SESSION Link to previous activity We have learnt about physical changes. Now let us learn about chemical changes.

Procedure 1 - Sulphur Take a clean gas jar, place a colored flower inside the gas jar. Take a small amount of sulphur powder in a deflagrating spoon. Introduce the sulphur inside the gas jar containing the flower. Ask the students to observe the gas jar carefully and write down their observations.

Now remove the spoon from the gas jar and light the sulphur with the spirit lamp. Sulphur starts burning, immediately. Again, introduce this burning sulphur inside the gas jar containing colored flower. Keep this undisturbed. Ask the students to observe the gas jar carefully and write their observations.

UNDERSTANDING THE ACTIVITY-1 Leading questions -1 1. What does sulphur look like at first?

2. What happens to the color of the flower when we introduce the sulphur into the gas jar?

3. What happens to sulphur when we heat it?

4. What happens to the color of the flower after we introduce the burning sulphur into the gas jar?

5. What happens after cooling the deflagrating spoon?

6. What could be the reason why we do not see sulphur in the deflagrating spoon after cooling?

7. How can you be sure that new substances have been formed?

8. How are the properties of the new product formed (sulphur dioxide) different from the properties of the sulphur?

9. What is such a change called?

10. What are some of the chemical changes you might have come across in your daily life?

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Discussion and Explanation-1 1. Sulphur is a pale yellow, powdery, crystalline substance 2. There is no change in the color of the flower 3. Sulphur turns into a liquid and releases a lot of smoke/fumes 4. The color of the flower fades, probably because of the smoke/fumes released 5. After cooling the deflagrating spoon, we see a black residue. Sulphur does not re-form 6. Sulphur goes through an irreversible, permanent change after heating and new products are formed.

This is why we do not see sulphur re-form in the deflagrating spoon after cooling 7. When we burn sulphur, we observed fumes coming out. These fumes are sulphur dioxide which was not present before burning the sulphur 8. When we expose the colored flower to sulphur powder, the color of the flower does not change. When the same flower is exposed to sulphur dioxide, its color changes. The properties of the new substances formed are therefore different from the properties of the original substances 9. An irreversible, permanent change where one or more new substances are formed, with a lot of energy either given out or absorbed is called a chemical change. A chemical change is also called a chemical reaction.

10. Some examples of chemical change - Souring/curdling of milk; burning of paper, coal, wood; rusting of iron nails; ripening of fruits; change in color of cut apple or brinjaletc Procedure 2 - Sugar Put half of the sugar in a small quantity of water and mix well. Boil the sugar and water mixture in a china dish until the solution becomes concentrated and the sugar starts to re-crystallize. Let the china dish cool for some time. Ask the students to observe the china dish carefully and write their observations. Take the other half of the sugar in the spatula and heat it over the spirit lamp. Keep the spoon aside for cooling. Ask the students to observe the spatula carefully and write their observations.

UNDERSTANDING THE ACTIVITY-2 Leading questions -2 1. What are the physical properties of sugar?

2. What happens to the sugar when it mixes with water?

3. What happens after the sugar solution in the china dish was boiled and cooled?

4. Does the sugar have the same color and state as it had earlier?

5. What happens when sugar is heated in the spatula?

6. Which is the physical change and which is the chemical change?

Discussion and Explanation-2 1. Sugar is in the form of small crystals. It is solid and white in color Agastya International Foundation. For Internal Circulation only.

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2. Sugar dissolves in the water to form sugar solution 3. Sugar crystals start reforming as the solutions gets more concentrated and more crystals form after the solution in the china dish is cooled 4. Yes, the sugar looks the same as it did earlier. It has the same color, state and shape 5. Sugar in the spatula slowly turns brown and then black. Water vapour fumes are seen and a black residue is left behind on the spatula 6. Dissolving sugar in water is a physical change. Heating sugar on the spatula is the chemical change Procedure 3 – Magnesium Tape Wear gloves and hold the magnesium strip. Cut the magnesium strip in half.Ask the students to observe and write their observations. Next, hold the magnesium strip with tongs and light it over the spirit lamp. Drop the burnt ash into the dustbin filled with sand. Ask the students to observe and write their observations.

UNDERSTANDING THE ACTIVITY-3 Leading questions -3 1. Did a new substance form when we cut the magnesium strip?

2. What happened to the magnesium tape when it was burnt?

3. What kind of change is this and why?

4. Did we get the magnesium strip back after it was burnt and why?

Discussion and Explanation-3 1. No, we got the same magnesium tape, but in a smaller size 2. Lots of smoke and light were emitted, and a white residue was left behind 3. A new substance is formed. It is a chemical change.

4. No, because this is a irreversible permanent change - a chemical change Procedure 4 – Activity Cards Distribute the activity cards – one set for each group. Ask the students to separate and place the physical change cards on the right hand side and the chemical change cards on the left hand side.

UNDERSTANDING THE ACTIVITY-4 Not Applicable Discussion and Explanation-4 Collect the answers and discuss them according to the answer key given below (Answer key: Frying of egg, rusting of nails and burning of wood are all examples of chemical changes; Slicing of vegetables, boiling of water and melting of ice are all examples of physical changes)

KEY MESSAGES 

Chemical change is usually a permanent change

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 

Change in composition takes place One or more new substances are formed

LEARNING CHECK: Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

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ABL 3 Changes in states of matter ABL

Learning Objective

3.1

Can matter change its state?

Key Messages  

3.2

How do solids change to liquids?

 



3.3

How do liquids change to gases?

 



 3.4

Can solids directly change into gases?





Time (min)

Matter can change from one state to another.

The change in state of matter can be brought about by applying heat or pressure.

10

Solids can be heated to turn into liquids.

The temperature at which a solid melts and forms a liquid is called as Melting Point.

The melting point is an indication of the force of attraction between the molecules of the substance; the stronger the force, the higher is the melting point.

15

When a liquid is heated, it turns into a vapour or gas.

The temperature at which the liquid turns into a gas is called its Boiling point.

The phenomenon of a liquid changing into vapour below its boiling point is called Evaporation.

Evaporation causes cooling.

20

Certain solids when heated directly turn into gases, without going through the liquid state.

This process of a solid turning into a gas directly is known as Sublimation.

20

Total Time

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ABL 3.1

Time: 10 min

LEARNING OBJECTIVE: Can matter change its state?

ADVANCE PREPARATION: Material List: S. No

Material

Quantity

1

Change in states of matter chart-1

1 per class

Things to Do: Not Applicable Safety Precautions: N/A

SESSION Link to known information/previous activity: Now that we know what states matter exists in, let us find out if it can change its state.

Procedure: Ask the class the following questions: -Can anyone name a substance that naturally exists as a liquid?

(Common answers could be water, milk, petrol, etc.)

-Do any of these also exist in solid state?

(Most common answer will be water existing as ice.)

-Do any of these exist in gaseous state?

(Some students might say water existing as water vapour.)

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Take the discussion forward by explaining to the class that matter exists in three forms- solid, liquid and gas.

However, substances can change from one form to another. Now display the Changes in States of Matter chart up in class and explain the following:

Chart 1- Changes in States of Matter We have already learnt that matter can exist in three different states- Solids, Liquids and Gases. Can matter change its state? Yes it can! A material will change its form depending upon the temperature and pressure applied on it. Since pressure is usually at atmospheric pressure, temperature is the major determining factor.

When heat is applied to a substance, it usually changes from solid to liquid to gas, in that order. Similarly when a material is cooled, it changes from gas to liquid to solid. To understand why this happens, we must understand that all the particles in a substance have a certain energy level. When you start heating the substance, it is like supplying external energy to the particles. When the energy level of the particles increases, they start moving around more and more. When the energy increases to a greater level, the particles can overcome the forces of attraction that hold them together, therefore changing from solid to liquid, or liquid to gas. This is what happens when we boil water, for example, and it turns from liquid to gas (water vapour).

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Upon the application of pressure, a gas can be changed to liquid. Some familiar examples are the gas cylinders we use at home for cooking our food. The cylinder is full of gas contained under very high pressure, which is why it is a liquid. You can hear the liquid move around in the cylinder when you move it.

UNDERSTANDING THE ACTIVITY: Leading Questions: 1.

2.

3.

4.

What factors can cause matter to change from one form to another?

How does temperature affect the substance and make it change its form?

Does matter always change from solid to liquid to gas/gas to liquid to solid?

Can you think of any other examples where pressure is used to change the state of a substance?

Discussion and Explanation: 1. Matter can change its form by the application of heat or pressure.

2. Remember we discussed that the particles in matter are attracted to each other and there are certain forces holding them together? When the temperature of a substance increases, the particles in it start to move around, due to the heat energy supplied to them. As the temperature is increased further, the particles overcome the forces of attraction between them, and are now free to move about. At this point, a solid changes into a liquid, and so on.

3. Certain substances can directly change from solids to gases and vice versa. This process is known as sublimation and we will learn more about it in the next ABL. 4. The oxygen cylinders that you can see in a hospital are also kept under high pressure in liquid form.

Many deodorants also pressurized.

KEY MESSAGES:  

Matter can change from one form to another.

The change in state of matter can be brought about by applying heat or pressure.

LEARNING CHECK: Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

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INTERESTING INFORMATION: Scientists are now thinking about FIVE states of matter. The two additions are PLASMA and BOSE-EINSTEIN CONDENSATES (BEC).

WEB RESOURCES: http://www.chem.purdue.edu/gchelp/atoms/states.html http://www.chem4kids.com/files/matter_states.html

Time: 15 min

ABL 3.2 LEARNING OBJECTIVE: How do solids change into liquids?

ADVANCE PREPARATION: Material List: S.No

Material

Quantity

1

Glass Beaker (250ml)

1 per group

2

Ice cubes

5-10 per group

3

Thermometers (Laboratory)

1 per group

4

Spirit Lamp

1 per group

5

Wire gauze

1 per group

6

Tripod Stand

1 per group

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SESSION Link to Previous Activity: Now that we have understood how temperature affects a substance, let us try and observe this practically.

Procedure: Divide the class into groups of four. Supply each group with the required materials, and help them set up their experiment as shown in the diagram below.

Fig 1: Melting of Ice Ask each group to place five ice cubes in the beaker. Note to Instructor- If ice is not available, you can use a small amount of Dalda or Vanaspati for this experiment. Do not light the spirit lamp yet. Place the thermometer in the beaker, and record the temperature of the ice cubes. Now light the spirit lamp and place it under the beaker. Observe the ice cubes in the beaker carefully. Record the temperature at the point when all of the ice cubes have completely melted, and you can see only water in the beak er.

UNDERSTANDING THE ACTIVITY: Leading Questions: 1. Why did the ice cubes turn into water?

2. At what temperature did all the ice cubes to turn into water?

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3. How long do you think it will take for ice cubes to turn into water at room temperature?

Discussion and Explanation: 1. The ice cubes turn into water due to the application of heat. As heat is supplied to the water molecules in the ice, the energy of the molecules increases. As they overcome the forces of attraction between them due to the heat energy supplied to them, they turn into water. This process is called melting.

2. The temperature at which a solid turns into a liquid is called its melting point. The melting point indicates how strong the forces of attraction between the molecules of that substance are. The higher the forces of attraction, the higher is the melting point. That means, if the forces of attraction are very strong, you will need to supply more energy to overcome the forces.

3. The ice cubes will take longer to melt at room temperature because no external heat energy will be supplied to them.

KEY MESSAGES:   

Solids can be heated to turn into liquids.

The temperature at which a solid melts and forms a liquid is called its Melting Point.

The melting point is an indication of the force of attraction between the molecules of the substance; the stronger the force, the higher is the melting point.

LEARNING CHECK: Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

Time: 20 min

ABL 3.3 LEARNING OBJECTIVE: How do liquids change to form gases?

ADVANCE PREPARATION: Material List: S.No

Material

Quantity

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1

Glass Beaker (250ml)

1 per group

2

Water

100 ml per group

3

Thermometers (Laboratory)

1 per group

4

Spirit Lamp

1 per group

5

Wire gauze

1 per group

6

Tripod Stand

1 per group

7

Acetone

1 ml per class

Things to Do: Not Applicable Safety Precautions: Not Applicable

SESSION Link to previous activity: We have done a small experiment to see how solids turn into liquids. Let us see what happens with liquids and gases.

Procedure: Retain the groups and experimental set up from the previous activity. Remove all the water from the beakers of each group and pour 100ml of fresh water into them. Ask learners to measure the temperature of water before lighting the spirit lamp and record it. Now light the spirit lamp and observe.

Make sure that the thermometer does not touch the base of the beaker.

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Fig 2: Boiling Point of Water Record the temperature at which the water starts bubbling. Ask learners to keenly observe the water, and record the temperature at which they can see steam appear on top of the beaker.

Put out the spirit lamp once the recordings have been made.

UNDERSTANDING THE ACTIVITY: Leading Questions: 1. At what temperature did the water start bubbling vigorously? At what temperature did you see steam appear?

2. Do you always need to apply heat for a liquid to change into a gas? Can you think of situations where a liquid turns to vapour without heating?

Discussion and Explanation: 1. Water starts to bubble and steam appears at almost the same time at 100oC. This temperature, at which the substance starts turning into vapour, is called its Boiling Point. The process of a liquid turning into vapour is called Vapourisation.

2. There are many occasions when water turns into vapour without the application of heat. The process where a liquid turns into vapour at a temperature below its boiling point is referred to as Evaporation.

When you mop the floor in your house, in some time all the water disappears. This is due to evaporation. Other common examples are washed clothes drying up, lakes and ponds drying up in summer, etc.

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Note to Instructor: At this point, call three volunteers forward and put a drop of acetone on each of their palms. Ask them to observe what happens, and then explain the following to your class: When a liquid evaporates, the particles try to regain the energy lost during evaporation, therefore taking energy from surroundings. Did you notice that when I put a drop of acetone on your hand, it immediately felt cool? The acetone takes the heat from your hand and evaporates. This is why your hand feels cool. This is also why you feel cooler when you sweat.

KEY MESSAGES:    

When a liquid is heated, it turns into a vapour or gas.

The temperature at which the liquid turns into a gas is called its Boiling point.

The phenomenon of a liquid changing into vapour below its boiling point is called Evaporation.

Evaporation causes cooling.

LEARNING CHECK: Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

TRY IT YOURSELF: Pour water into 3 transparent plastic cups, marking the level of water carefully in each one. Place one in direct sunlight, one under the fan, and one in a closed cupboard. Observe the cups and the level of water in four hours. What does this experiment tell you about evaporation?

(Answer for Instructor’s Reference: The rate of evaporation is very high for the cups placed in sunlight and under the fan. The water level in these cups has drastically decreased. The cup placed inside the cupboard does not lose water as fast as the other two cups. This tells us that sunlight and wind/breeze are major factors that affect evaporation.

ABL 3.4 LEARNING OBJECTIVE: Can solids directly change to gases?

ADVANCE PREPARATION: Material List: Agastya International Foundation. For Internal Circulation only.

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Time: 20 min

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S.No

Material

Quantity

1

China Dish

1 per class

2

Glass Funnel

1 per class

3

Cotton

A tiny ball

4

Spirit Lamp

1 per group

5

Wire gauze

1 per group

6

Tripod Stand

1 per group

7

Iodine Crystals/Camphor

A few crystals

Things to Do: Not Applicable Safety Precautions: Not Applicable

SESSION: Procedure: Retain the set up from the previous activity. Remove the beaker and replace it with a china dish. Place a few crystals of Iodine crystals/camphor on the china dish. Invert the thistle funnel and place it over the dish. Plug the other end of the thistle funnel with a cotton plug and make sure it is closed properly.

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Fig 3: Sublimation of Iodine Now light the spirit lamp and ask the students to observe the crystals of iodine/camphor .

UNDERSTANDING THE ACTIVITY: Leading Questions: 1.

2.

3.

4.

What happens to the crystals when you heat them?

Did you observe any liquid in the dish?

Does the thistle funnel look any different? What has happened to it?

Can you think of any other substances that undergo sublimation?

Discussion and Explanation: 1. As we begin to heat the crystals, it starts emitting some vapours.

2. No liquid can be observed in the china dish. This is because the camphor has sublimated to form vapours directly, without going through the liquid phase.

3. You can see deposits of a brownish/whitish material on the surface of the thistle funnel. As the vapours of iodine/camphor rise up, they come in contact with the thistle funnel and immediate cool.

As they cool, they return to the original solid state.

4. Substances like Odonil and naphthalene balls that we use for getting rid of insects, both undergo sublimation. Next time you open a bar of odonil, keep an eye on it for a few days, you will notice the size of the bar decreasing!

KEY MESSAGES:  

Certain solids when heated directly turn into gases, without going through the liquid state.

This process of a solid turning into a gas directly is known as Sublimation

LEARNING CHECK: Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

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ABL 4–Introduction to Elements, Compounds, and Mixtures Activity

Learning objective

Key messages

Time (min)

4.1

In what form do atoms occur in our environment?

4.2

How are atoms combined to form different substances?

4.3

What are pure and impure substances?

4.4

How are mixtures classified?



All substances occur in the form of elements, compounds or mixtures  The smallest unit to which a substance/matter can be broken down is an atom.  Elements and compounds are made up of atoms.  Elements are made up of only one kind of atom  Compounds are made up of atoms of different elements chemically combined together  Mixtures are made up of different elements and/or compounds that are physically mixed together  Substances can be pure or impure  A pure substance is made of only one kind of material. It could be an element or a compound  An impure substance is made up of many different materials mixed together.  Mixtures can be either homogenous or heterogeneous  Substances are uniformly mixed in homogenous mixtures  Substances are unevenly mixed in heterogeneous mixtures Total Time

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10

15

15

30

70

39

ABL 4.1

Time: 10 min

LEARNING OBJECTIVE –In what forms do atoms occur in our environment?

Note to Instructor –Learners need to have a basic prior knowledge that the smallest unit of matter is an atom. For further details you can refer C5 - Atomic structure ABL1.

ADVANCE PREPARATION Material List 1

Material Glass of water

Number Required 1 per class

Things to do Not Applicable

Safety Precautions Not Applicable

SESSION Link to known information/previous activity We all know that all matter is made up of atoms and that matter occurs in different states. Now let us explore how exactly these atoms exist in our environment.

Procedure Show learners the glass of water and ask them a set of leading questions to help them understand the concept of elements, compounds and mixtures.

Note to Instructor - This is only an introduction and you need not go into details. They only need to be introduced to the definitions and the fact that these three things are not interchangeable terms.

UNDERSTANDING THE ACTIVITY Leading questions 1. What is in the glass? Is it a pure substance?

2. What are the components that make up water? Can I break this water down into its components?

3. Can I further break up Hydrogen and Oxygen atoms into their components?

4. Do Hydrogen and Oxygen always form water under all conditions? Why not?

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Discussion and Explanation 1. The glass contains water. Yes water is a pure substance because it does not contain anything other than water. (Some learners may say it is impure and has germs etc. In that case, tell them that the water is filtered to remove impurities like germs and dirt and ask them the question again.)

2. The chemical formula for water is H2O. Hence, the components of water are Hydrogen and Oxygen. We can break down water molecules into Hydrogen and Oxygen atoms by a very powerful, high-energy process called hydrolysis/electrolysis.

3. Hydrogen and Oxygen atoms cannot be broken down further as they are already in the most basic state. They contain one type of atom in them and are called elements. Water, on the other hand, is a combination of these elements in a specific proportion (2 Hydrogen atoms and 1 Oxygen atom per molecule of water as we can see from the chemical formula). This type of substance is called a compound. Compounds can be broken down into their base elements.

4. Hydrogen and Oxygen do not always combine to give water. They will do so only under specific conditions of pressure and temperature. These conditions of temperature and pressure existed when the Earth was formed and that is why Earth is the only planet to have water on it. Similarly, there is no evidence of water on other planets even though their atmosphere contains some amounts of Hydrogen and Oxygen. Otherwise, they will just exist together in a space in their native form. This is called a mixture. In a mixture, the elements exist together in no specific ratio, in their own states and do not combine chemically to give rise to any new substance. For example, Hydrogen, Oxygen, Nitrogen and so many other gasses form the most common mixture that surrounds us, namely, Air.

KEY MESSAGES  

All substances occur in the form of elements, compounds or mixtures.

The smallest unit to which a substance/matter can be broken down is an atom.

LEARNING CHECK: Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the key messages chart. If you have time during the class, make up a small game or quiz or match the following as a learning check. This may have to be done as part of advance preparation.

TRY IT YOURSELF Gather small amounts of rice, rava and maida. They are made of small particles, but each particle of rice is the same throughout the container. It is the same for rava and maida.

Place a small amount of rice first on a plate. Are the particles visible? Now remove the rice from the plate and place the rava on a plate and spread it out. Can you see the particles of rava? Now remove the rava and place Agastya International Foundation. For Internal Circulation only.

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maida on the plate. It is hard to see each particle of maida. Atoms and molecules are much, much smaller than the smallest particle of maida. You need powerful tools to see atoms and molecules.

ABL 4.2

Time: 15 min

LEARNING OBJECTIVE - How are atoms combined to form substances?

Note to Instructor – Here we talk about element, compounds and mixtures. Stress on the chemically combining together versus physically mixing together of substances.

ADVANCE PREPARATION Material List Material 23. 1 tbsp.Iron filings in a cup

Number Required 1 per class

24. 1tbsp.Sulphur in a cup

1 per class

25. 1 empty cup

1 per class

26. 2 spatulas

1 per class

27. 1 china dish

1 per class

28. 1 tripod stand

1 per class

29. 1 wire gauze

1 per class

30. 1 spirit lamp

1 per class

31. 1 matchbox

1 per class

32. 1 bar magnet

1 per class

33. Observation Sheet 1 (Elements and compounds) 1 per learner (print out only half the – Worksheet 1 quantity required – there are two sheets per page) Elements & Compounds - Observation Sheet 1.docx

34. Large copy of Observation Sheet 1(Elements and compounds)– Worksheet 2

1 per class

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Worksheet 2 ecm.docx

Things to do Print enough copies of Observation sheet 1.

Label the cup with Iron filings as “Cup 1” and the cup with Sulphur as “Cup 2”.Label the empty cup as “Cup 3”.

Set up the apparatus for the experiment. Place the spirit lamp under the tripod stand. Place the wire gauze on top of the tripod stand. Make sure that the windows and doors are open so that the classroom is wellventilated. Place the Large Observation Sheet 1 in a prominent place, such as taped to the blackboard/whiteboard.

Safety Precautions Tell the learners to keep a safe distance and not to touch any of the materials or apparatus used in the experiment. Take care to wash the china dish immediately after the experiment to prevent Iron and Sulphur from getting stuck in the dish.

SESSION Link to known information/previous activity We have learnt that atoms are the building blocks of matter. Now let us see how these building blocks are joined together.

Procedure 4.2a Show Cup1 with Iron filings and Cup2 with Sulphur to all the learners. Ask them to observe the color and texture of the materials.

Call one or two learners to move the magnet over Cup1 with Iron filings.

Next, call one or two other volunteers to move the magnet over Cup2 containing Sulphur.

Now,invite two new volunteers to pour half of the Iron filings and half of the Sulphur into Cup3 and mix the two materials with a spatula. Show Cup3 to all the learners. Invite one or two learners to move the magnet over cup 3.

Distribute copies of the Observation Sheet 1 to all learners.Ask them to enter their observations in Observation Sheet 1.

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UNDERSTANDING THE ACTIVITY Leading questions 4.2a 1. What are the Iron filings made of?

2. What happens when we move the bar magnet over the cup containing Iron filings?

3. What is Sulphur made of?

4. Are there any other types of atoms in Cup1 and Cup2?

5. What atoms are present in Cup3 with Iron and Sulphur mixed together?

6. What happens when we move the bar magnet over the cup containing Iron filings and Sulphur?

7. When we put Iron and Sulphur together and mix it with a spatula does anything change?

Discussion and Explanation 4.2a 1. Iron filings are made of Iron atoms 2. The Iron filings stick to the magnet 3. Sulphur is made of Sulphur atoms 4. Cup1 and Cup2 contain only one kind of atom – Cup 1 contains Iron atoms and Cup2 contains only Sulphur atoms. Both Iron and Sulphur are known as elements. Solids such as Gold, Silver, and Carbon as well as liquids such as Bromine and Mercury are examples of elements.

5. It contains both atoms of Iron as well as atoms of Sulphur 6. Iron filings from the cup stick to the magnet, while the Sulphur remains in the cup 7. Even though they are mixed together, Iron remains in the form of Iron filings and behaves like Iron. Iron atoms retain their magnetic property. Sulphur exists as granules and behaves like Sulphur. Such a substance is called a mixture. In a mixture, two or more substances are mixed together physically. They retain their original properties. Solids such as soil, liquids such as tea, sugar water etc. are examples of mixtures.

Procedure 4.2b Now pour the Iron-Sulphur mixture from into a china dish and place the china dish on the tripod stand so that it is stable. Light the spirit lamp and heat. A black mass of Iron sulphide is formed. A lot of heat is released during this process.

Invite one or two learners to move the magnet over the black mass of Iron sulphide after the reaction is over.

Ask them to enter their observations in Observation Sheet 1.

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UNDERSTANDING THE ACTIVITY Leading questions 4.2b 1. When we put Iron and Sulphur together in the china dish and heat it does anything change?

2. What happens when we move the bar magnet over the black lump of Iron sulphide?

3. How is the new substance formed in the china dish, different from the Iron and Sulphur in Cup3?

4. How are compounds different from mixtures?

5. What are the building blocks of compounds?

6. How come elements are made of atoms and compounds are made of molecules?

7. Do elements have molecules too?

Discussion and Explanation 4.2b 1. The Iron and Sulphur react and form a black lump. This new substance is Iron sulphide 2. Nothing is attracted to the magnet, the new substance formed by the chemical reaction between Iron and Sulphur does not have the magnetic property 3. In Cup3, Iron and Sulphur are mixed together physically, but retain their original properties. They can be separated. But when we heated it, a new substance has been formed. This substance has properties that are different from that of Iron and Sulphur. The atoms of Iron and Sulphur have combined together to form a new substance – Iron sulphide. This new substance is called a compound.

Compounds cannot be separated into their original components easily.

4. Compounds are atoms of different substances that have chemically combined together in a fixed ratio to form molecules of the new substance. Mixtures contain atoms of different substances, which can be physically combined in any ratio. No new substance is formed in a mixture.

5. A molecule is the “building block” of a compound. It is the smallest unit that a compound can be divided into so that it still behaves like a compound.

6. Both elements and compounds are made of atoms. The new substance formed – Iron sulphide– contains molecules of the compound Iron sulphide. The smallest unit of the compound Iron sulphide that behaves like Iron sulphide is a molecule. But these molecules in turn are made up of atoms, which are the smallest units of the elements Iron and Sulphur.

7. Sometimes atoms of elements also join together to form molecules of the element. For example, Oxygen gas is made up of molecules. Each molecule contains two atoms of Oxygen element.

KEY MESSAGES    

Elements and compounds are made up of atoms Elements are made up of one kind of atom Compounds are made up of atoms of different elements chemically combined together Mixtures are made up of different elements and/or compounds that are physically mixed together

LEARNING CHECK The following multiple-choice questions can be given out as a worksheet or can be conducted as a quick quiz in the class.

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1. The smallest unit of an element that has all the basic properties of the element is called: a. An atom b. A molecule c. An element d. A compound 2. A molecule is the smallest complete unit of: a. An atom b. An element c. A compound d. A mixture 3. A substance that cannot be broken down further by physical means is called: a. An element b. A compound c. A mixture d. A solution

4. Which statement about atoms and molecules is correct? a. Elements always exist as separate atoms b. Elements always exist as molecules of two atoms c. Elements and compounds can exist as single atoms d. Elements and compounds can exist as molecules 5. Which statement about compounds is incorrect? a. A compound has different properties than the substances that react to form it b. A compound has all the properties of the substances that react to form it c. A compound can be formed by both elements and other compounds d. A compound is a chemical combination of substances in fixed ratios

Answers for Instructor’s reference: (Ans. key: 1.a, 2.c, 3.a, 4.d, 5.b)

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ABL 4.3

Time: 35 min

LEARNING OBJECTIVE –What are pure and impure substances?

Time – 15 mins

Note to Instructor –Pure substances contain only one type of material in them. They could be elements or compounds. Impure substances are made up of different materials. These are mixtures including solutions.

Material 1. 1 tbsp.Iron filings

Number Required 1 per class

2. 2tbsp.common salt

1 per class

3. 1 tbsp.sugar

1 per class

4. 2tbsp.jeera powder

1 per class

5. 1 large container water

1 per class

6. 6 empty plastic containers

1 per class

7. Plastic stirrers

5 per class

8. Large Observation sheet 2 – Mixtures - Worksheet 3

1 per class

Things to do Prepare small packets of sugar (1 packet), salt (2 packets), jeera (2packets) and Iron filings (1 packet) by wrapping the material in a piece of paper and label the packet.

Place the Large Observation Sheet 2 in a prominent place, such as taped to the blackboard/whiteboard.

Safety Precautions Remind the learners that they should not taste the substances.

SESSION Link to known information/previous activity We now know that substances can be identified as elements, compounds and mixtures. Let us now learn more ways of grouping substances.

Procedure Divide the learners into five groups. Give each group a given set of ingredients (as per the list below) and ask them to prepare a mixture using the given ingredients in the container provided and stir it well.

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Group 1 – Empty cup, water, salt packet, stirrer Group 2 – Empty cup, water, jeera packet, stirrer Group 3 – Empty cup, water, sugar packet, stirrer Group 4 – Empty cup, water, Iron filings packet, stirrer Group 5 – Empty cup, salt packet, Jeera packet, stirrer

Ask them to observe if the substance in the packets and the substance in the cup have one kind of material or many.

After all groups have made their mixtures. Ask them to take a minute to discuss their observations and send one person from their group to come and present their finding to the class. That learner must come in front with the mixture and then tell you what to fill into the large observation sheet.

You can use the leading questions to help the learner answer as you fill in the observation sheet.

Finally show them the sixth cup containing just water and ask learners to make observations about the water and fill in the last column of the observation sheet.

Leading questions 1. Which of these substances have only one kind of material?

2. Which of these substances have more than one kind of material?

3. How can compounds be considered a pure substance?

4. Why are mixtures considered impure substances?

Discussion and Explanation 1. Water, sugar, salt and Iron filings have only one kind of material. These are elements and compounds and are called “pure substances”.

2. Salt&jeera, sugar water, salt water, jeera water and Iron filings water are mixtures and are made of more than only one kind of material. These are called “impure substances” 3. Although, compounds are chemically combined from elements, they are considered a pure substance.

They cannot be broken down into further substances. The smallest unit of a compound is a molecule of a compound.For example, common salt or sodium chloride is a compound and a pure substance. It is made Agastya International Foundation. For Internal Circulation only.

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by chemically combining sodium and chlorine in a fixed proportion. It is a pure substance because it cannot be broken down into sodium and chlorine by physical means. Its smallest unit is a molecule of sodium chloride. Every molecule of common salt is the same as every other molecule in the substance 4. Mixtures are physical combinations of any substances in any proportion. Salt water is a mixture of two pure substances, salt and water, that can be made by combining one spoon of salt and one glass of water, or 2 spoons of salt and half a glass of water.They can easily be separated by physical means.

KEY MESSAGES   

Substances can be pure or impure.

A pure substance made of only one kind of material. It could be an element or a compound.

An impure substance is made up of many different materials mixed together. An impure substance is called a mixture.

LEARNING CHECK True or False?

1.

2.

3.

4.

5.

6.

1.

2.

3.

4.

5.

6.

The element Gold is a pure substance.

The compound Carbon dioxide is an impure substance Water is made of Hydrogen and Oxygen.

Water is a compound and can be broken down into Hydrogen and Oxygen by heating.

Mixtures are made of two or more substances that can be physically separated Sugar water is a pure substance Answers for Instructor’s reference: (T) (F) Carbon dioxide is a pure substance although it is a compound (T) (F)Water is a compound and it cannot be broken down by physical means (T) (F) Even though sugar water is a solution, it can be physically separated into its component parts by physical means. It is an impure substance

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Time: 30 min

ABL 4.4 LEARNING OBJECTIVE – How are mixtures classified?

1.

Material 1 tbsp.Iron filings

Number Required 1 per class

2.

1 tbsp. common salt

1 per class

3.

1 tbsp. sugar

1 per class

4.

1tbsp. jeera powder

1 per class

5.

1 large container water

1 per class

6.

1 per class

7.

9 empty plastic containers with lids. (Small, transparent plastic bottles) Plastic stirrers

8.

Black board/ White board to write on

1 per class

1 per class

Things to do Place sugar in container (C1), salt (C2). Mix small amounts of jeera, salt and sugar together in a container (Container C3). Prepare sugar water (C4), salt water (C5), sugar+salt +water (C6), jeera water (C7) and Iron filings + water (C8). Keep plain water (C9). Label these containers as C1 to C9 in that order.

Safety Precautions Remind the learners that they should not taste the substances.

SESSION Link to known information/previous activity We have learnt that mixtures are impure substances because they are physical combinations of more than one kind of material that are mixed in any proportion. Now let us see andlearn about different types of mixtures.

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Procedure-1 Pass containers 1 through 9 around the class. Ask the learners to observe the contents of each container carefully and pass it to the next person. Once they have done so, take all the containers back and quickly discuss their observations using the leading questions. Make sure you hold a container up to the learners when you are talking about it.

Leading questions-1 1. Can you identify the mixtures by looking at them?

2. How can you identify the substances as mixtures?

3. What are these types of mixtures called?

4. Can you think of some more examples of heterogeneous mixtures?

Discussion and Explanation-1 1. It is clear that C3 (sugar, salt and jeera mixture), C7 (jeera water) and C8 (Iron filings water) are mixtures.

2. We can easily see the different substances mixed together, so they must be mixtures.

3. Mixtures in which we can see each substance separately and which do not mix uniformly, no matter how much we mix them, are called “heterogeneous mixtures�

4. A mixture of oil and water is heterogeneous. No matter how much we shake it, or mix it or heat it, the oil and water are visible separately

Procedure-2 Write down the contents of each container on the board so that the learners now know what each container had in it. Ask them to think about the contents of the containers that they observed and discuss their observations using the leading questions.

Leading questions-2 1. Now, after reading the contents, can you identify the mixtures?

2. Mixtures in C4, C5 and C6 are exactly like plain water in C7. Why do you identify these substances as mixtures?

3. What are these types of mixtures called?

4. Can you think of some more examples of homogeneous mixtures?

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Discussion and Explanation-2 1. Now we see that container C4 (sugar water), C5 (salt water) and C6 (sugar and salt water) also contain mixtures.

2. Although sugar water, salt water and sugar+salt water look exactly like plain water, we know that they are mixtures because they contain more than one substance 3. Mixtures which are uniformly mixed, where the substances are not visible separately are called “homogeneous mixtures” 4. Air is a homogeneous mixture of gases. The gases, Nitrogen, Oxygen and Carbon dioxide that are in the mixture are uniformly mixed.

KEY MESSAGES   

Mixtures can be either homogenous or heterogeneous Substances are uniformly mixed in homogenous mixtures Substances are unevenly mixed in heterogeneous mixtures

FIGURE 4 – Classification of Matter (Include this image in Key message chart)

LEARNING CHECK:

Note to Instructor – This is a learn-by-doing activity in which the learner understands how to differentiate between elements, compounds and mixtures. This can be used as a comprehensive evaluation for this entire ABL. Gather all the materials mentioned below and place them on a table. Label the material clearly.

Draw 4 large (non-intersecting) circles in the classroom with the chalk and label them “Elements”, “Compounds”, “Homogeneous Mixtures” and “Heterogeneous Mixtures”.

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Material 1. 1 bottle distilled water

Number Required 1 per class

2. 1 bottle coca cola

1 per class

3. 1 piece of wood

1 per class

4. 1 plastic plate (plain white)

1 per class

5. 1 sheet of lined/ruled paper

1 per class

6. 1 bottle of ketchup

1 per class

7. 1 packet of sambar powder

1 per class

8. 1 bowl nuts, bolts and washers

1 per class

9. 1 packet of salt

1 per class

10. 1 packet of sugar

1 per class

11. 1 packet of washing powder

1 per class

12. 1 bar of washing soap

1 per class

13. 1 aluminium vessel

1 per class

14. 1 copper vessel (not tinned on the inside)

1 per class

15. 1 piece of chalk for drawing

1 per class

Tell the learners that you will all now play a fun game to see how much they have learnt in this ABL. Explain to the learners that you will call out the name of each material and hand it to a learner and he/she has to go and stand inside the circle in which the item belongs.

Pick up one the materials one at a time and call out its name loudly. Ask one of the learners to go take the item and stand inside the circle to which the item belongs. In case a learner goes to a circle to which the item does not belong, explain which is the correct circle and why. Call out the next item and the name of the next learner. Continue until all the items are placed in the circles.

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Answers for Instructor’s reference: (Elements: Distilled water, Copper vessel, Aluminium vessel; Compounds: salt, sugar and plastic plate (polymer); Mixtures: Coca cola, wood piece, paper, ketchup, sambar powder, bowl of nuts, bolts and washers, washing powder, bar soap)

INTERESTING INFORMATION A sample of matter is called a heterogeneous mixture when we can see two or more phases separated by boundaries. The phases might be a solid and a liquid, such as fibrous material suspended in water, or two liquids, like oil and water (you may have seen this as a sign of pollution in the ocean), or other combinations of solids, liquids, and gases. The components of heterogeneous mixtures can usually, but not always, be separated by simple mechanical processes such as filtering or decanting. For example, we could separate the fibrous material from a suspension in water by pouring the mixture into a coffee filter. The water passes through and the fiber is collected on the paper. The oil and water can be separated by allowing the mixture to stand and then carefully decanting the less dense, oil layer from the more dense, water layer.

Some mixtures are only recognized as heterogeneous when observed through a microscope. Cold cream (ex: Ponds or Vicco turmeric), for example, is an emulsion consisting of very fine droplets of oil and water.

When a sample of matter appears to be the same throughout, i.e. a single uniform phase even at very high magnification, it is referred to as homogeneous. A homogeneous sample may consist of a single chemical substance, or it may be a mixture of two or more different substances. Homogeneous mixtures are also called solutions, a term that is most familiar when one of the components is a liquid. For example, a solution of sodium chloride (table salt) in water is homogeneous. Any sample taken from the original solution would taste the same, and would have salt and water in the same proportions. Air is another well- known homogeneous mixture, consisting primarily of the gases Nitrogen, Carbon dioxide and Oxygen. Solid homogeneous mixtures of metals are called alloys. 'Gold' used in jewellery is usually a mixture of gold with copper and other metals. Stainless steel is a mixture of Iron, chromium, and nickel.

Homogeneous mixtures often have their own unique properties. Bronze is composed of copper and tin.

Bronze is harder than both copper and tin, individually. This is why bronze was chosen as the material to make tools during the Bronze Age. Note to Instructor – Refer C7- Metals and Non-metals ABL3 The components of a homogeneous mixture can usually be separated by taking advantage of the different properties of the individual components. Distillation is a common technique in which a mixture is heated until Agastya International Foundation. For Internal Circulation only.

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the component that boils at the lowest temperature becomes a vapour and can be separated. The vapour can be cooled and collected in a separate vessel, and the other components of the mixture are left in the original flask. Another important separation process is chromatography. You may have used paper from a coffee filter to separate the components of an ink or dye for example https://www.youtube.com/watch?v=3ZP_E0eTmMU Homogeneous mixtures can have variable composition. Let's consider salt solutions. We can make salt solutions by dissolving salt in water in just about any proportions we choose. The exact properties of the solution, how salty it tastes for example, will depend on the proportions. A solution of salt in water conducts electricity, but the amount of current that can be carried depends on the amount of salt dissolved in a given volume of water. To describe a mixture completely, we need to give not only the identity of the components of which it is composed but also the relative amounts of the components.

WEB RESOURCES http://www.mrwilsonscience.com/Mr._Wilson_Science/Blog-_Chem-L2/Blog-_ChemL2_files/1.%20%20Matter%20-%20Pure%20%26%20Impure.pdf http://www.teachengineering.org/view_activity.php?url=collection/uoh_/activities/uoh_sep_mixtures_activit y1/uoh_sep_mixtures_activity1.xml

REFERENCES: 1. National Council of Educational Research and Training, Class IX, October 2013.

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Observation sheet 1: What is a chemical change?

Name: Class:

Activity

School:

Describe before change (colour, state, size etc)

What was happening during change?

Describe after change

Melting of wax Heating of sulphur Dissolving of sugar Heating sugar Cutting of Mg strip Heating of Mg strip

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Is it a temporary or a permanent change?

Why?

Is it a chemical or physical change?

Why?

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Observation sheet 2: What are pure and impure substances?

Name: Class:

School:

Place a tick mark for each substance to indicate whether it is “Pure” or “Impure”. Enter substance names for each kind of impure substance.

Substance

Pure (only one kind of substance)

Impure (more than one kind of substance)

Iron filings Common salt Salt &jeera Sugar water Salt water Jeera water Iron filings water Water

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