Natural Sciences2nd YearTerm 2

Phases of Matter

Metals & Non-metals Processing materials

Name and Surname: ________________________________________Year group: ____________________

Introduction: MatterDate:___________________

In the past you have often heard us talk about matter. The word matter refers to

everything that has mass and occupies space. Literally all of the things that you can

observe around you are forms of matter. The furniture in a room, the objects on the

table or on the floor, the flowers outside, the birds and animals, water and all the

other liquids; yes, everything is matter.

Furniture Table with objects. Flowers in a garden.

Birds and animals. Water such as a river. A cup of tea.

But now you must remember that there are also certain forms of matter that you

cannot see. Just think of the gases in the air which you have already learned about.

They are not visible but, because they also occupy space and have mass, we must

regard them as examples of matter.

To summarise we can thus say that matter is the material from which things around us are made of.

2

So what is matter made of? All matter is made of atoms. Atoms are the smallest

particle of matter. They are so small that you cannot see them with your eyes or

even with a standard microscope.

Atoms Microscope

Let us look at a few concepts first:

Solid

Solids are objects that are firm and stable. They hold their shape and they

could be hard, soft, big or small. E.g. a chair, when you move a chair to

another place, it will still have the same shape.

Liquid

Liquids flow and take on the shape of the container they are in. Therefore we can

say that it has no fixed shape. E.g. bottled water.

Gas

Do you remember in the first term when we spoke about breathing as one of the

seven life processes of living things? When we breathe, we are taking in and giving

out gases. But we cannot see the gas. Gases are everywhere around us. They are

free-flowing and one can easily put your hand through them. E.g. the air you

breathe.

Gases are a bit more difficult to understand as we usually cannot see gases. We

can see places where gases are used and the containers that gas is kept in.

3

Cooking using a gas stove. A patient with an oxygen mask.

Balloons filled with helium or air. A scuba diver with oxygen in his back.

Evaporation

This process takes place when heat is added to the liquid. It means

the water changes from a liquid state to a gas state. Think about

hanging your clothes out to dry in the sun. They dry as the water

evaporates.

Condensation

The steam that comes from a boiling kettle or pot is extremely hot and you cannot

see it. The steam quickly cools down and form tiny droplets in the air. These tiny

droplets are visible and form the ‘cloud’ that you see. When these tiny droplets hit

the mirror they cool more and form the bigger droplets which you can see. We say

steam condensed to form water. The change of state is from gas to liquid.

Freezing / Solidifying

This process takes place when a liquid forms a solid when cooled down. E.g. ice

lollies are made from a liquid. The liquid is poured into the shape of an ice lolly

and then cooled, as heat is removed they freeze.

Melting

This process takes place when a solid turns into a liquid when heat is added. E.g.

when ice lollies are left in the sun.

Activity 1

1. Name the following objects.

4

___________________ ______________________

2. _______________ are objects that are firm, stable and they hold their shape.

3. The process that takes place when a liquid turns into a gas when heat is

added is known as _______________________.

4. ______________ are everywhere around us. They are free-

_____________________.

5. The process that takes place when a solid turns into a liquid when heat is

added is known as _______________________.

6. The process that takes place when a gas cools down and forms a liquid is

known as _______________________.

7. __________________ flows and take on the shape of the container they are

in.

8. The process that takes place when a liquid forms a solid when cooled down is

known as ______________________.

Phases of MatterDate:___________________

5

“Tom did you know…? A water molecule is formed when two atoms

of hydrogen join with one atom of oxygen…”

We’ve seen that matter usually exists in one of three states or phases: solid, liquid,

or gas. The chair you are sitting on is a solid, the water you drink is liquid, and the air

you breathe is a gas. Matter changes state when more energy gets added to it.

Energy is often added in the form of heat or pressure.

During the previous period we said that solids are objects that are firm and stable.

They hold their shape and room temperature; and they could be hard, soft, big or

small. This is matter that is composed of atoms packed tightly together. You cannot

walk through a solid wall. The matter is packed so tightly that it prevents you from

moving through it. Think about this; the pencil that you left on the desk at school will

still be the same shape when you return tomorrow. Examples of solids: table, chair,

door, wall, window, car, flower, tree, house, stationery, garbage bin etc.

Liquids flow and take on the shape of the container they are in. They do not hold

their shape at room temperature. There is space between the atoms of a liquid and

they move slightly all of the time. This allows you to stick your finger into water and

6

“What is meant by room temperature?It refers to the air temperature not being

specifically heated or cooled.”

pull it back out, letting the water fill back in where your finger once was. But when

walking through the water in a swimming pool, you have to push the water out of the

way – this means that you feel the heaviness of the water. Liquids cannot be

handed to another person without a container. Imagine going into a

restaurant and asking for lemonade. What if the waiter just put the

lemonade into your hands – no glass or cup? Could you lay the lemonade

on the table to drink in a few minutes? Even water in a river or lake has a

container – the banks, the bottom, the shore – they form the container.

Examples of liquids: water, ocean, tea, coffee, juice, sodas, rain, milk,

medicine syrups etc.

Gases are everywhere around us. They are free-flowing (always moving) and one

can easily put your hand through them. They don’t hold their shape at room

temperature and don’t stay put. There is so much space between the atoms in gas

that you can move around in them easily. When you walk from one

side of the room to the other, you have walked through a bunch of

gases that make up our air. You barely even know they are there.

Examples of gas: oxygen, nitrogen, water-vapour, clouds, steam etc.

Activity 2

1. Look at the pictures below. Decide if they are a ‘solid’, ‘liquid’ or a ‘gas’?

__________________ ___________________ ___________________

7

__________________ ___________________ ___________________

__________________ ___________________ ___________________

Matter: Changing from PhaseDate:___________________

Before we look at matter changing from phase, let’s just study the summary below.

Solid Liquid GasHas a definite shape. Has no definite shape. Has no definite shape.

Takes up a definite space. Takes up a definite space. Takes up any/all the space

available.

Do not flow. Can flow. Can flow.

During the introduction of matter we’ve seen that matter can change from one phase

to another. E.g. when ice melts; a solid changes into a liquid.

8

Think about the following:

If you place tap water into an ice tray and put this in the freezer, what will

happen to the water?

If you take ice cubes and place them in the sun, what happens to the ice

cubes?

The difference between the freezer and the sun outside is that one is hot and the

other is cold. So if we place the water in a place that is cold enough, it freezes. If

we place the ice cubes in a hot place, they melt.

Study the illustration below about the phase changes of matter.

Notice when gas condenses (small drops of water) it is turned into liquid and

when liquid evaporates (changes into steam) it is turned into gas.

Notice when a solid melts (add heat) it is turned into liquid and when a liquid

freezes (extreme low temperature) it is turned into solids.

Some substances melt very easily, while others need to be heated for a while.

Each substance starts melting at a certain temperature. This is called the

melting point of a substance. Temperature is measured in degrees Celsius (ºC),

9

with an instrument called a thermometer.

Here is a summary of the different phase changes:

Change of phase ‘Heating’ or ‘Cooling’ Process is called…..Solid to a liquid Heating Melting

Liquid to a gas Heating Evaporation

Gas to a liquid Cooling Condensation

Liquid to a solid Cooling Freezing

Activity 3

Read the following story and answer the questions that follow.

Giovanni’s Lesson

Giovanni Blaauw is a boy in Grade 1 at a primary school in a small village which gets very hot during the summer. He loves to play soccer. After school he often goes over to The Thunderbolt School of Learning to play with the Thunderbolt Kids. They really like having Giovanni there to play with them, even though he is a few years younger, because he is very talented and also fun and caring. Giovanni especially likes Johnique and they play well together as a team.

One day after school, Giovanni thought he would do something nice for his friends, the Thunderbolt Kids and surprise them with ice lollies, when they were done playing. Giovanni bought 5 ice lollies, one for himself and one for each of the Thunderbolt Kids. He put the ice lollies in a bowl and placed some ice blocks around them to keep them cool. Giovanni then ran off to join the others playing soccer.

After the game, Giovanni ran back to the bowl to get the ice lollies. But he got such a shock when he got there. They were all gone! He was so upset and started to cry. The Thunderbolt Kids saw that Giovanni was upset and ran over to see what was wrong.

"Hey Giovanni, what's wrong? Did you hurt yourself while playing?" Johnique asked.

"No, I didn't. I bought some ice lollies for all of you as a surprise and when I came back now to get them they were all gone! I think someone stole and ate them and just left the sticks! Look!" Giovanni cried out.

"Oh no, don't cry Giovanni! It's not your fault, and no one stole them or ate them either," Wharick said while rubbing Giovanni on the back.

"Yes, Giovanni, actually we learnt in class today about what happened to your ice lollies," said Devon, "and I can explain it to you too. Do you see that your bowl is actually not empty? There is a liquid in it. It also has a red colour, which was the colour of your ice lollies."

"Yes, I see that," answered Giovanni, "but then how did that happen?"

10

Denise then answered, "Your ice lollies melted from the heat from the air around us. Even if the sun was not so hot, they would have melted! For something to stay frozen it needs to be at a very cold temperature, like in a freezer."

"Yes, melting is when heat causes the solid ice lollies to change into a liquid," Devon replied, "So no one stole the ice lollies, they just melted."

"Oh ok, I see," said Giovanni, "I must be really silly not to know that!"

"No, not at all Giovanni! We only learned about it today in class and we are in Grade 4!" laughed Wharick.

"I know what we should do!" shouted Johnique, "Let's go to the tuck-shop right now. I have some extra change and we can buy some more frozen ice lollies!"

They all really liked this idea, especially Giovanni who was now laughing. So off they all went, the Thunderbolt Kids and Giovanni, and bought some more ice lollies and sat under the tree to eat them.

QUESTIONS:

1. What is the name of the main character in the story?

__________________________________

2. What grade is he in?

______________________

3. What grade are the Thunderbolt Kids in?

______________________

4. What game are the children playing together after school?

______________________

5. When the ice lollies are frozen, are they a solid, liquid or a gas?

11

______________________

6. Explain in your own words what happened to the ice and the ice lollies while

they were left in the sun.

______________________________________________________________

______________________________________________________________

7. What is the name of this process?

__________________________

8. Do you think you can reverse the process of melting? How?

______________________________________________________________

9. What is your favourite type of ice cream or ice lolly?

___________________________

10. If you wanted to do something nice for your friends, what would you do?

______________________________________________________________

______________________________________________________________

Metals and Non-metalsDate:___________________

How can I tell if something is made of a metal or a non-metal? How do we decide

what material to use when we want to make or build something? These are some of

the questions that we will be looking at.

Metals and non-metals are two different classes of materials. Each class has its own

unique properties. Properties are those things that are special about an object or a

material. We can use properties of a material to describe what it is like. When we

want to make a new product we first have to decide what the purpose of that product

will be. Perhaps we want to make a tool for digging in the garden, or a kennel (dog

12

house) for our new puppy. The purpose of the product will help us decide which

would be the best material to use when making the object.

What would be the best material for a digging tool? Surely we would need a tool that

is strong and durable; with a sharp edge that will allow us to cut through the soil

when we dig into it.

Let us look at a few concepts first:

Natural materialMaterial that is found naturally on Earth, it can be collected from animals, plants,

rocks or the ground.

Synthetic (manufactured) materialWhen something is man-made it is called synthetic.

Metals

Metals are strong, shiny and hard. It is a natural compound. They are known to

conduct heat very well and can be shaped without breaking or cracking. E.g. copper,

aluminium, zinc, gold, silver, brass, lead, iron, tin, titanium etc.

PolymersMany modern products are polymers. It is a synthetic (man-made) compound. E.g.

nylon, polyester, polystyrene, teflon, plastic, wool, silk, rubber etc.

CeramicsThese products are exposed to extreme high temperatures. They are manufactured

from any product made of a non-metallic mineral like clay, thus making it a synthetic

(man-made) compound. E.g. porcelain, tiles, bricks, glass, stoneware etc.

13

Look at the following table to see how types of materials are classified.

Natural material Synthetic material Wool

Cotton

Wood

Silk

Leather

Oil

Gold

Coal

Sand (soil)

Plastic

Glass

Paper

Paint

Nylon

Porcelain

Bricks

Tiles

Activity 4

Study the two pictures below and answer the questions that follow.

1. What material was used to build house A?

______________________________________________________________

2. What material was used to build house B?

______________________________________________________________

14

3. If you had to build a house next to the ocean, which one would you choose

AND why?

______________________________________________________________

______________________________________________________________

4. Write down three other materials that could be used for building a house.

__________________________

__________________________

__________________________

5. What is a ‘natural material’?

______________________________________________________________

6. Where do we obtain natural materials from?

__________________________

__________________________

__________________________

7. What does it mean if something is ‘synthetic’?

______________________________________________________________

8. Name two examples of a metal.

__________________________

__________________________

9. Name two examples of a polymer.

__________________________

__________________________

10.Name two examples of a ceramic.

__________________________

__________________________

15

Properties: MetalsDate:___________________

Now that we have looked at the different types of materials that you could use to

build a house with, let us look at the different properties of metals and non-metals.

Remember we said that properties are those characteristics that make something

special or different to others.

Good question Tom! Let’s look at the properties of metals.

Metals are usually shiny. The shine that we see when light

reflects off the surface of a metal is called the lustre (shiny

appearance) of the metal.

Most metals are hard and they feel heavy.

We say metals are dense as they have particles which are packed close

together. (Remember earlier in the term when we spoke about solids.)

Metal conduct electricity and heat very well. Meaning that you could be

shocked if a metal touches electricity and you could get severely burnt if you

touch a metal that was heated.

Metals are malleable and ductile (can easily be shaped into some-

thing else).

Most metals can be heated to high temperatures without melting or

changing their shape, which is one of the reasons why pots and pans are

made of metal.

Metals are mined from the Earth.

Activity 5: Investigation

16

“So how can we tell if something is made out of metal?”

Your teacher will have the following objects ready for you in class. This will help you

to experience the properties of metals. The aim of this investigation is to identify the

properties that metals have.

Material supplied by teacher:

Coins

Metal spoon

Metal pencil sharpener

Metal nail or screw

Paper clip or thumb tack

Steel wool

Metal bottle cap

A few metal objects are placed on the teacher’s table. Notice all of the different

shapes.

1. Write the name of each object in the table.

2. Hold each object in your hand. Does it feel hot or cold? Rough or smooth?

3. Look at each object carefully. Is it shiny or dull? Can you describe its colour?

4. Drop each object on the floor or tap it on the table. What sound does it make?

5. Write your observations in the table below. (you may use of the words in the word bank

below)

shiny, dull, rough, hard, smooth, cold, warm, heavy, rigid, sharp, flexible, soft, light

Picture Name of the object How does the object feel when you touch it?

What does the object look like?

17

18

Properties: Non-metalsDate:___________________

Now that we have looked at the properties of metals, let us take a look at the

properties of non-metals. Remember properties are characteristics that make

objects special or different to others.

That is easy Kim! Non-metals are materials that do not have the same properties as

metals. Let’s look at the properties of non-metals.

Non-metals are not shiny but tend to be dull.

Many non-metals are not bendy but brittle. This means that they will break

when we try to bend them with enough force.

Some non-metals could be soft or flexible like rubber.

Non-metals do not have the ability to rust.

Non-metals do not conduct electricity or heat very well. We call them

insulators. That is one of the reasons why pots and pans often have plastic or

wooden handles.

This kettle is made from metal

and has a plastic handle.

19

“How can we tell if something is made of a non-metal?”

Activity 6: Investigation

Your teacher will have the following objects ready for you in class. This will help you

to experience the properties of non-metals. The aim of this investigation is to

identify the properties that non-metals have.

Material supplied by teacher:

Paper or cardboard

Cotton wool

Fabric

Plastic spoon

Cork

Sponge

Piece of glass

A few metal objects are placed on the teacher’s table. Notice all of the different

shapes.

1. Write the name of each object in the table.

2. Hold each object in your hand. Does it feel hot or cold? Rough or smooth?

3. Look at each object carefully. Is it shiny or dull? Can you describe its colour?

4. Drop each object on the floor or tap it on the table. What sound does it make?

5. Write your observations in the table below.

20

“Tom, do we clean metals and non-metals in the same way?”

“That is an interesting question, Kim. Depending on the material the method will be different. Metals can be polished with a fine cloth or rubbed with a

paste made of pumice (silver-grey rock) powder and water. Non-metals can be cleaned by using a fine

cloth or washed with soap and water.”

Picture Name of the object How does the object feel when you touch it?

What does the object look like?

21

Processing materialsDate:___________________

When we combine materials, new materials are made. The properties of new

materials are often different from the properties of the materials we started with.

Remember properties are things that make an object unique or different to others.

There are many ways to process materials into new materials. There are also many

reasons why we would wish to process materials into new materials.

When we bake a cake we are processing flour, eggs and other ingredients

(that may not taste very nice on their own) into a cake which tastes really good!

We process materials to make them stronger, or more durable (staying in a good

condition), or waterproof, or even just to make them look more attractive or

interesting. New materials that form after mixing different materials are sometimes

called mixtures.

Let us look at a few concepts first:

MixingThis happens when two or more substances are added together.

Combining

The act of combining is to form a new substance, by mixing different substances

together.

22

Mmmm… Yum! I think I am going to enjoy this chapter if we

are going to bake cakes!

SettingThis is when the mixture is given time to cool down after a certain process.

Cooking/HeatingWhen there is an increase in the temperature of the mixture.

CoolingWhen there is a decrease in the temperature of the mixture.

DryingThis means allowing the moisture or liquid to be evaporated from the mixture by

increased temperatures such as sunlight, wind or heating.

Let us have a look at a few processed materials and the reasons why they are

processed.

Stainless SteelWe’ve learnt that iron rusts over time, and that this process speeds up when the iron

is in contact with water. Have you ever noticed rust on the knives and forks in your

home? Probably not! That is because they are not made of iron but stainless steel.

But what is stainless steel?

Stainless steel is made by combining iron with other metals to make it stronger and

to prevent it from rusting. By processing iron with other metals to turn it into

stainless steel means we can use it even in wet environments. Water taps and pipes

are often made of stainless steel. Some of the instruments that doctors use to

operate with on sick people are made of stainless steel, and so are the pots and

pans that we use when we prepare food.

23

Stainless steel taps. A shiny pot made out of stainless steel.

Jelly Have you ever tasted jelly? To make jelly, we have to dissolve jelly powder in hot

water. When the solution of jelly powder in water cools down, something very

special happens… The solution sets, and turns into a delightfully wobbly, sweet

treat! The jelly powder has been processed into something new!

ConcreteHave you ever watched builders mix concrete when they want to build a wall or a

house? The people in the picture below are mixing sand and water with building

cement. The mixture of sand, water and cement is called concrete. Concrete is like

mud when it is wet, but when it dries out it sets into a hard, strong material.

Concrete can be used to make bricks and pavements or to plaster a wall.

Mixing concrete using spades.

In this first picture people are using spades to mix the concrete. They are using the

spades like we would use a spoon to stir sugar into a cup of coffee or tea. The

people are using their muscles to do the work required for mixing concrete. In the

next picture the machine is called a cement mixer. This machine mixes all of the

24

ingredients by turning mechanically, like an electric food mixer. Electrical energy

does the work required for mixing concrete.

A cement mixer.

CookingCooking or preparing food is also a form of processing. Have you ever seen what a

raw egg looks like? The same egg looks quite different when it is cooked or fried.

Notice how the egg white is transparent when it is raw and white when it is cooked.

When it is raw, the egg is runny like liquid. When it is cooked the egg is solid but soft

like rubber or plastic. Look at the examples below.

A raw egg. An egg after being fried (cooked).

Activity 7

1. List two reasons why we process materials.

______________________________________________________________

______________________________________________________________

2. Write down a definition for ‘mixing’.

______________________________________________________________

3. What is stainless steel?

______________________________________________________________

______________________________________________________________

25

4. Why do you think cutlery is made out of stainless steel?

______________________________________________________________

5. After jelly powder has been mixed with hot water and placed in a refrigerator

the mixture ______________ into a delightful wobbly treat.

6. What do concrete consist of?

_______________________

_______________________

_______________________

7. Name the following object.

________________________

Processing materials (continues)Date:___________________

We call materials that have not yet been processed raw materials. Raw materials

are made into other things. When raw materials are in the form in which they are

found in nature, we call them natural materials. A natural material is any material

that comes from plants, animals or the ground.

We have learnt that there are many different ways in which materials can be

processed to give them new properties. After processing they may look, smell, feel

or taste different. They will probably also be used for a totally different purpose than

before.

Processed materials are materials which have been refined or built by humans from

raw materials. Some examples are paper, steel and glass.

26

Materials that have been processed are very useful to us because they have some

special properties. We already know that processed materials can be strong and

durable. But what other properties do they have? Look at the following examples:

Gumboots are waterproof. An umbrella is waterproof. Paint has different colours.

Safety boots are for protection. Bread is processed from wheat. Wine is processed from grapes.

We know that people have been processing materials from the earliest of times. In

the olden days only natural materials were available and people found many clever

ways to make these materials more useful.

The first people who lived in our country had ways to harden wood and bone for

making tools and hunting weapons. They also had ways of reinforcing (making

stronger) the mud used for making traditional huts. They knew which materials

made the best clothes, blankets and which grass made the softest beds. They also

knew exactly which reeds (plants) would make the best mats to cover their walls,

and how to build the best houses for their climate and lifestyle.

Look at the list of processed material:

27

Bread

Rice

Maize meal

Toothpaste

Honey

Meat

Sausage

Metal – and wooden furniture

Leather shoes

Petrol

Necklace made of shells

Paper

Paint

Instruments

Stationery etc.

Activity 8

1. What is a ‘natural material’?

______________________________________________________________

2. List two examples of natural material.

_______________________

_______________________

3. What is ‘processed material’?

______________________________________________________________

4. List two examples of processed materials.

_______________________

_______________________

5. What do gumboots, an umbrella and a rain jacket have in common?

28

______________________________________________________________

6. What unique property does paint have?

______________________________________________________________

7. What is the purpose of safety boots?

______________________________________________________________

8. What is bread processed mainly from?

__________________________

9. What is wine processed mainly from?

__________________________

10.What do you think the following homes are made of?

__________________________________ _________________________________

_________________________________ _______________________________

*****

29