Textbook: Elements and Compounds | Technical Science for Grade 10 PDF Download

 Page 1


 technical science GRADE 10 219
chapter 9 elements and compounds
In Chapter 8 you learned about the properties of materials. In this chapter you learn about the 
atoms that make up those materials. Here is a map to show where we are going in Chapters 8 
to 11.
…but here we 
answer them!
In chapter 8 we study 
materials on the macro-
scale. We study, for 
example, strength, density, 
magnetic properties, 
melting and boiling.
In chapter 9 we study 
materials on the nano-
scale; that is, the atoms 
and molecules that 
make up the materials 
and use the PKMM.
chapter 10 uses the 
PKMM to understand how 
elements and compounds 
react and how ions form.
chapter 8 leaves some 
questions unanswered about 
the properties of materials… 
what are the reasons why these 
materials have these properties?
In chapter 11 we use the PKMM to answer 
the questions about:
 ? why some materials are magnetic
 ? how they conduct heat and electricity
 ? why boiling points depend on altitude
In this chapter you learn about the atoms that make up materials. Briefl y:
•	 Pure substances can be compounds or elements.
•	 Compounds are made from two or more elements, and compounds can be broken down 
into their elements.
•	 Each element has its own kind of atom and its own symbol in the periodic table.
•	 Each kind of atom has a structure made of protons, neutrons and electrons that occupy 
different energy levels.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   219 2015/12/17   10:03 AM
Page 2


 technical science GRADE 10 219
chapter 9 elements and compounds
In Chapter 8 you learned about the properties of materials. In this chapter you learn about the 
atoms that make up those materials. Here is a map to show where we are going in Chapters 8 
to 11.
…but here we 
answer them!
In chapter 8 we study 
materials on the macro-
scale. We study, for 
example, strength, density, 
magnetic properties, 
melting and boiling.
In chapter 9 we study 
materials on the nano-
scale; that is, the atoms 
and molecules that 
make up the materials 
and use the PKMM.
chapter 10 uses the 
PKMM to understand how 
elements and compounds 
react and how ions form.
chapter 8 leaves some 
questions unanswered about 
the properties of materials… 
what are the reasons why these 
materials have these properties?
In chapter 11 we use the PKMM to answer 
the questions about:
 ? why some materials are magnetic
 ? how they conduct heat and electricity
 ? why boiling points depend on altitude
In this chapter you learn about the atoms that make up materials. Briefl y:
•	 Pure substances can be compounds or elements.
•	 Compounds are made from two or more elements, and compounds can be broken down 
into their elements.
•	 Each element has its own kind of atom and its own symbol in the periodic table.
•	 Each kind of atom has a structure made of protons, neutrons and electrons that occupy 
different energy levels.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   219 2015/12/17   10:03 AM
220 c hapter 9 ELEMENTS AND COMPOUNDS
unit 9.1 The classification of matter
The physical world is made up of a huge number of different substances. Scientists have 
discovered or made over 10 million different substances. But all those substances are made 
from only about 100 simpler substances called elements.
Ten million substances is far too many to study and even to put in one list. We need a method 
to group the substances and make it easier to study them. The method is called classification.
To understand classification, think of a big supermarket – 
you go in there to buy some soap but you see a great number 
of different products on the shelves. There’s rice and tea 
and washing powder and oil and milk and nailbrushes and 
mugs and eggs and face cream.
If these products were all mixed up you’d need hours to find 
the soap. But the supermarket sorts the products and so you 
find the soap on the shelf marked “Personal care products”. 
Soap is there with deodorant, toothpaste and face-cream; 
these are personal care products and they are on the same 
shelf.
The supermarket manager has sorted the products into 
groups or classes, using some rule of what things belong 
together. We say that the manager has classified them.
“Personal care products” is a broad classification, and 
within that group we may find soap (four different kinds 
of soap), shampoo (three kinds of shampoo), and so on.
Figure 9.2 This is a 
classification diagram for 
items in a supermarket.
All products
Personal
care
Food
Soaps
Brushes
Brooms
Small dishes
Large pots
Knives
Scissors
Shampoos
Face creams
Dried food
Canned food
Fresh food
Cutting tools
Cooking pots
Cleaning tools
Kitchenware
Figure 9.1 A supermarket sorts its 
products and it groups similar kinds of 
products together.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   220 2015/12/17   10:03 AM
Page 3


 technical science GRADE 10 219
chapter 9 elements and compounds
In Chapter 8 you learned about the properties of materials. In this chapter you learn about the 
atoms that make up those materials. Here is a map to show where we are going in Chapters 8 
to 11.
…but here we 
answer them!
In chapter 8 we study 
materials on the macro-
scale. We study, for 
example, strength, density, 
magnetic properties, 
melting and boiling.
In chapter 9 we study 
materials on the nano-
scale; that is, the atoms 
and molecules that 
make up the materials 
and use the PKMM.
chapter 10 uses the 
PKMM to understand how 
elements and compounds 
react and how ions form.
chapter 8 leaves some 
questions unanswered about 
the properties of materials… 
what are the reasons why these 
materials have these properties?
In chapter 11 we use the PKMM to answer 
the questions about:
 ? why some materials are magnetic
 ? how they conduct heat and electricity
 ? why boiling points depend on altitude
In this chapter you learn about the atoms that make up materials. Briefl y:
•	 Pure substances can be compounds or elements.
•	 Compounds are made from two or more elements, and compounds can be broken down 
into their elements.
•	 Each element has its own kind of atom and its own symbol in the periodic table.
•	 Each kind of atom has a structure made of protons, neutrons and electrons that occupy 
different energy levels.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   219 2015/12/17   10:03 AM
220 c hapter 9 ELEMENTS AND COMPOUNDS
unit 9.1 The classification of matter
The physical world is made up of a huge number of different substances. Scientists have 
discovered or made over 10 million different substances. But all those substances are made 
from only about 100 simpler substances called elements.
Ten million substances is far too many to study and even to put in one list. We need a method 
to group the substances and make it easier to study them. The method is called classification.
To understand classification, think of a big supermarket – 
you go in there to buy some soap but you see a great number 
of different products on the shelves. There’s rice and tea 
and washing powder and oil and milk and nailbrushes and 
mugs and eggs and face cream.
If these products were all mixed up you’d need hours to find 
the soap. But the supermarket sorts the products and so you 
find the soap on the shelf marked “Personal care products”. 
Soap is there with deodorant, toothpaste and face-cream; 
these are personal care products and they are on the same 
shelf.
The supermarket manager has sorted the products into 
groups or classes, using some rule of what things belong 
together. We say that the manager has classified them.
“Personal care products” is a broad classification, and 
within that group we may find soap (four different kinds 
of soap), shampoo (three kinds of shampoo), and so on.
Figure 9.2 This is a 
classification diagram for 
items in a supermarket.
All products
Personal
care
Food
Soaps
Brushes
Brooms
Small dishes
Large pots
Knives
Scissors
Shampoos
Face creams
Dried food
Canned food
Fresh food
Cutting tools
Cooking pots
Cleaning tools
Kitchenware
Figure 9.1 A supermarket sorts its 
products and it groups similar kinds of 
products together.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   220 2015/12/17   10:03 AM
 technical science GRADE 10 221
In Science we can also do sorting and classifying. In the diagram below, you see how all 
substances can be sorted into three classes. 
All substances
Solids
Liquids
Gasses
Figure 9.3 A classification diagram for all substances. The groups are based 
on the state of the substance; that is, whether it’s a solid, a liquid or a gas.
Quick activity:
1. Use Figure 9.3 and name four solids, four liquids and two gases you can find in a 
supermarket.
2. Thinking of the supermarket, name two solids that are metals and two solids that are 
non-metals.
Now we are going to classify substances in another way. We will classify all substances into the 
two classes mixtures and pure substances.
Look at the classification diagram in Figure 9.4. You see that some substances are mixtures but 
other substances are pure substances. Of the pure substances, some are elements and some 
are compounds.
All substances
Mixtures
Elements
Pure substances
Compounds
Figure 9.4 This is another way to classify all substances. The groups are based on what 
the substances are made from.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   221 2015/12/17   10:03 AM
Page 4


 technical science GRADE 10 219
chapter 9 elements and compounds
In Chapter 8 you learned about the properties of materials. In this chapter you learn about the 
atoms that make up those materials. Here is a map to show where we are going in Chapters 8 
to 11.
…but here we 
answer them!
In chapter 8 we study 
materials on the macro-
scale. We study, for 
example, strength, density, 
magnetic properties, 
melting and boiling.
In chapter 9 we study 
materials on the nano-
scale; that is, the atoms 
and molecules that 
make up the materials 
and use the PKMM.
chapter 10 uses the 
PKMM to understand how 
elements and compounds 
react and how ions form.
chapter 8 leaves some 
questions unanswered about 
the properties of materials… 
what are the reasons why these 
materials have these properties?
In chapter 11 we use the PKMM to answer 
the questions about:
 ? why some materials are magnetic
 ? how they conduct heat and electricity
 ? why boiling points depend on altitude
In this chapter you learn about the atoms that make up materials. Briefl y:
•	 Pure substances can be compounds or elements.
•	 Compounds are made from two or more elements, and compounds can be broken down 
into their elements.
•	 Each element has its own kind of atom and its own symbol in the periodic table.
•	 Each kind of atom has a structure made of protons, neutrons and electrons that occupy 
different energy levels.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   219 2015/12/17   10:03 AM
220 c hapter 9 ELEMENTS AND COMPOUNDS
unit 9.1 The classification of matter
The physical world is made up of a huge number of different substances. Scientists have 
discovered or made over 10 million different substances. But all those substances are made 
from only about 100 simpler substances called elements.
Ten million substances is far too many to study and even to put in one list. We need a method 
to group the substances and make it easier to study them. The method is called classification.
To understand classification, think of a big supermarket – 
you go in there to buy some soap but you see a great number 
of different products on the shelves. There’s rice and tea 
and washing powder and oil and milk and nailbrushes and 
mugs and eggs and face cream.
If these products were all mixed up you’d need hours to find 
the soap. But the supermarket sorts the products and so you 
find the soap on the shelf marked “Personal care products”. 
Soap is there with deodorant, toothpaste and face-cream; 
these are personal care products and they are on the same 
shelf.
The supermarket manager has sorted the products into 
groups or classes, using some rule of what things belong 
together. We say that the manager has classified them.
“Personal care products” is a broad classification, and 
within that group we may find soap (four different kinds 
of soap), shampoo (three kinds of shampoo), and so on.
Figure 9.2 This is a 
classification diagram for 
items in a supermarket.
All products
Personal
care
Food
Soaps
Brushes
Brooms
Small dishes
Large pots
Knives
Scissors
Shampoos
Face creams
Dried food
Canned food
Fresh food
Cutting tools
Cooking pots
Cleaning tools
Kitchenware
Figure 9.1 A supermarket sorts its 
products and it groups similar kinds of 
products together.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   220 2015/12/17   10:03 AM
 technical science GRADE 10 221
In Science we can also do sorting and classifying. In the diagram below, you see how all 
substances can be sorted into three classes. 
All substances
Solids
Liquids
Gasses
Figure 9.3 A classification diagram for all substances. The groups are based 
on the state of the substance; that is, whether it’s a solid, a liquid or a gas.
Quick activity:
1. Use Figure 9.3 and name four solids, four liquids and two gases you can find in a 
supermarket.
2. Thinking of the supermarket, name two solids that are metals and two solids that are 
non-metals.
Now we are going to classify substances in another way. We will classify all substances into the 
two classes mixtures and pure substances.
Look at the classification diagram in Figure 9.4. You see that some substances are mixtures but 
other substances are pure substances. Of the pure substances, some are elements and some 
are compounds.
All substances
Mixtures
Elements
Pure substances
Compounds
Figure 9.4 This is another way to classify all substances. The groups are based on what 
the substances are made from.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   221 2015/12/17   10:03 AM
222 c hapter 9 ELEMENTS AND COMPOUNDS
Mixtures 
A mixture is two or more substances mixed together so 
that if you take a sample (a small piece) you will always 
find all the substances together in it. For example, if you 
poured salt and sugar into a bag and shook it, you would 
have a salt-and-sugar mixture. If you tasted the mixture, 
you would get both tastes together. But it would still be a 
salt-and-sugar mixture, not some new substance. 
homogeneous mixtures
If you mixed sugar and water in a cup and stirred the 
mixture well, you would have an even mixture. That is to 
say, the mixture from the bottom of the cup would taste 
the same as the mixture from the top of the cup – the 
mixture is the same all the way through. In science, an 
even mixture is called a homogeneous mixture.
In Chapter 8 you learned about alloys. An alloy is a solid 
that is a mixture of elements that has the properties of 
metals. An example of an alloy is solder. Solder that you 
use for electronics is 37% lead and 63% tin, and we can say 
that the lead is dissolved in the tin.
This may sound strange, to talk about a solid solution. 
But look at Figure 9.5 and Figure 9.6. You could do this 
activity. Dissolve a crayon in hot, molten candle-wax and 
stir it. When the solution cools you have an even, solid 
solution of coloured wax in white wax.
Most of the substances that you know are 
mixtures
Most kinds of food and drink are mixtures, and the air 
that you breathe is a mixture of gases. Air has about 21% 
oxygen, 78% nitrogen, and small amounts of argon and 
carbon dioxide and other gases, including water vapour.
The gas that people use for cooking is a mixture of two 
gases, and the exhaust gas from a car is carbon monoxide 
mixed with a number of other gases. 
Quick activity:
Why must a car engine have an oil filter? What does the 
filter do? 
Figure 9.5 The coloured crayon 
dissolves in the hot, molten candle wax.
Figure 9.6 When the wax cools, we 
have a solid solution of coloured wax 
in white wax.
Figure 9.7 You might test exhaust gas 
to measure the percentage of carbon 
monoxide in the gas.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   222 2015/12/17   10:03 AM
Page 5


 technical science GRADE 10 219
chapter 9 elements and compounds
In Chapter 8 you learned about the properties of materials. In this chapter you learn about the 
atoms that make up those materials. Here is a map to show where we are going in Chapters 8 
to 11.
…but here we 
answer them!
In chapter 8 we study 
materials on the macro-
scale. We study, for 
example, strength, density, 
magnetic properties, 
melting and boiling.
In chapter 9 we study 
materials on the nano-
scale; that is, the atoms 
and molecules that 
make up the materials 
and use the PKMM.
chapter 10 uses the 
PKMM to understand how 
elements and compounds 
react and how ions form.
chapter 8 leaves some 
questions unanswered about 
the properties of materials… 
what are the reasons why these 
materials have these properties?
In chapter 11 we use the PKMM to answer 
the questions about:
 ? why some materials are magnetic
 ? how they conduct heat and electricity
 ? why boiling points depend on altitude
In this chapter you learn about the atoms that make up materials. Briefl y:
•	 Pure substances can be compounds or elements.
•	 Compounds are made from two or more elements, and compounds can be broken down 
into their elements.
•	 Each element has its own kind of atom and its own symbol in the periodic table.
•	 Each kind of atom has a structure made of protons, neutrons and electrons that occupy 
different energy levels.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   219 2015/12/17   10:03 AM
220 c hapter 9 ELEMENTS AND COMPOUNDS
unit 9.1 The classification of matter
The physical world is made up of a huge number of different substances. Scientists have 
discovered or made over 10 million different substances. But all those substances are made 
from only about 100 simpler substances called elements.
Ten million substances is far too many to study and even to put in one list. We need a method 
to group the substances and make it easier to study them. The method is called classification.
To understand classification, think of a big supermarket – 
you go in there to buy some soap but you see a great number 
of different products on the shelves. There’s rice and tea 
and washing powder and oil and milk and nailbrushes and 
mugs and eggs and face cream.
If these products were all mixed up you’d need hours to find 
the soap. But the supermarket sorts the products and so you 
find the soap on the shelf marked “Personal care products”. 
Soap is there with deodorant, toothpaste and face-cream; 
these are personal care products and they are on the same 
shelf.
The supermarket manager has sorted the products into 
groups or classes, using some rule of what things belong 
together. We say that the manager has classified them.
“Personal care products” is a broad classification, and 
within that group we may find soap (four different kinds 
of soap), shampoo (three kinds of shampoo), and so on.
Figure 9.2 This is a 
classification diagram for 
items in a supermarket.
All products
Personal
care
Food
Soaps
Brushes
Brooms
Small dishes
Large pots
Knives
Scissors
Shampoos
Face creams
Dried food
Canned food
Fresh food
Cutting tools
Cooking pots
Cleaning tools
Kitchenware
Figure 9.1 A supermarket sorts its 
products and it groups similar kinds of 
products together.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   220 2015/12/17   10:03 AM
 technical science GRADE 10 221
In Science we can also do sorting and classifying. In the diagram below, you see how all 
substances can be sorted into three classes. 
All substances
Solids
Liquids
Gasses
Figure 9.3 A classification diagram for all substances. The groups are based 
on the state of the substance; that is, whether it’s a solid, a liquid or a gas.
Quick activity:
1. Use Figure 9.3 and name four solids, four liquids and two gases you can find in a 
supermarket.
2. Thinking of the supermarket, name two solids that are metals and two solids that are 
non-metals.
Now we are going to classify substances in another way. We will classify all substances into the 
two classes mixtures and pure substances.
Look at the classification diagram in Figure 9.4. You see that some substances are mixtures but 
other substances are pure substances. Of the pure substances, some are elements and some 
are compounds.
All substances
Mixtures
Elements
Pure substances
Compounds
Figure 9.4 This is another way to classify all substances. The groups are based on what 
the substances are made from.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   221 2015/12/17   10:03 AM
222 c hapter 9 ELEMENTS AND COMPOUNDS
Mixtures 
A mixture is two or more substances mixed together so 
that if you take a sample (a small piece) you will always 
find all the substances together in it. For example, if you 
poured salt and sugar into a bag and shook it, you would 
have a salt-and-sugar mixture. If you tasted the mixture, 
you would get both tastes together. But it would still be a 
salt-and-sugar mixture, not some new substance. 
homogeneous mixtures
If you mixed sugar and water in a cup and stirred the 
mixture well, you would have an even mixture. That is to 
say, the mixture from the bottom of the cup would taste 
the same as the mixture from the top of the cup – the 
mixture is the same all the way through. In science, an 
even mixture is called a homogeneous mixture.
In Chapter 8 you learned about alloys. An alloy is a solid 
that is a mixture of elements that has the properties of 
metals. An example of an alloy is solder. Solder that you 
use for electronics is 37% lead and 63% tin, and we can say 
that the lead is dissolved in the tin.
This may sound strange, to talk about a solid solution. 
But look at Figure 9.5 and Figure 9.6. You could do this 
activity. Dissolve a crayon in hot, molten candle-wax and 
stir it. When the solution cools you have an even, solid 
solution of coloured wax in white wax.
Most of the substances that you know are 
mixtures
Most kinds of food and drink are mixtures, and the air 
that you breathe is a mixture of gases. Air has about 21% 
oxygen, 78% nitrogen, and small amounts of argon and 
carbon dioxide and other gases, including water vapour.
The gas that people use for cooking is a mixture of two 
gases, and the exhaust gas from a car is carbon monoxide 
mixed with a number of other gases. 
Quick activity:
Why must a car engine have an oil filter? What does the 
filter do? 
Figure 9.5 The coloured crayon 
dissolves in the hot, molten candle wax.
Figure 9.6 When the wax cools, we 
have a solid solution of coloured wax 
in white wax.
Figure 9.7 You might test exhaust gas 
to measure the percentage of carbon 
monoxide in the gas.
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   222 2015/12/17   10:03 AM
 technical science GRADE 10 223
pure substances
Pure substances are not mixtures. Pure substances are a single type of material.
There are two kinds of pure substances: compounds and elements.
compounds
You probably know many compounds from your Natural Sciences in Grade 9. You may know 
names that end in “-ide”, such as sodium chloride (called table salt), iron oxide (called rust), 
mercuric oxide, potassium chloride and of course carbon dioxide.
Dry ice Dry ice 45 minutes later
Figure 9.8 “Dry ice” or “steam ice” is really carbon dioxide in the solid state.
Perhaps you know names that end with “-ate”, like 
sodium carbonate (called washing soda), sodium 
bicarbonate (called baking soda), potassium 
permanganate (called amanyazin, makganatsohle 
and Condy’s crystals) and magnesium sulfate  
(called Epsom Salts).
Many other substances have common names that 
hide the fact they are compounds: water, ammonia, 
and igali (tartaric acid).
In nature, most substances are compounds and there 
are millions of different compounds. 
Pure carbon dioxide is a compound, but you can 
guess from the name “carbon dioxide” that it is made 
from two elements, carbon and oxygen. 
Figure 9.9 Some common compounds
TechSci_G10-LB-Eng-DBE3_9781431522842.indb   223 2015/12/17   10:03 AM