NCERT Textbook: Metals & Non-metals | Science & Technology for UPSC CSE PDF Download

 Page 1


Metals and Non-metals
3 CHAPTER
I
n Class IX you have learnt about various elements. You have seen
that elements can be classified as metals or non-metals on the basis of
their properties.
n Think of some uses of metals and non-metals in your daily life.
n What properties did you think of while categorising elements
as metals or non-metals?
n How are these properties related to the uses of these elements?
Let us look at some of these properties in detail.
3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSICAL PROPERTIES AL PROPERTIES AL PROPERTIES AL PROPERTIES AL PROPERTIES
3.1.1 Metals
The easiest way to start grouping substances is by comparing their
physical properties. Let us study this with the help of the following
activities. For performing Activities 3.1 to 3.6, collect the samples of
following metals – iron, copper, aluminium, magnesium, sodium, lead,
zinc and any other metal that is easily available.
Activity 3.1 Activity 3.1 Activity 3.1 Activity 3.1 Activity 3.1
n Take samples of  iron, copper, aluminium and magnesium. Note
the appearance of each sample.
n Clean the surface of each sample by rubbing them with sand paper
and note their appearance again.
Metals, in their pure state, have a shining surface. This property is
called metallic lustre.
Activity 3.2 Activity 3.2 Activity 3.2 Activity 3.2 Activity 3.2
n Take small pieces of iron, copper, aluminium, and magnesium.
Try to cut these metals with a sharp knife and note your
observations.
n Hold a piece of sodium metal with a pair of tongs.
CAUTION: Always handle sodium metal with care. Dry it by
pressing between the folds of a filter paper.
n Put it on a watch-glass and try to cut it with a knife.
n What do you observe?
2024-25
Page 2


Metals and Non-metals
3 CHAPTER
I
n Class IX you have learnt about various elements. You have seen
that elements can be classified as metals or non-metals on the basis of
their properties.
n Think of some uses of metals and non-metals in your daily life.
n What properties did you think of while categorising elements
as metals or non-metals?
n How are these properties related to the uses of these elements?
Let us look at some of these properties in detail.
3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSICAL PROPERTIES AL PROPERTIES AL PROPERTIES AL PROPERTIES AL PROPERTIES
3.1.1 Metals
The easiest way to start grouping substances is by comparing their
physical properties. Let us study this with the help of the following
activities. For performing Activities 3.1 to 3.6, collect the samples of
following metals – iron, copper, aluminium, magnesium, sodium, lead,
zinc and any other metal that is easily available.
Activity 3.1 Activity 3.1 Activity 3.1 Activity 3.1 Activity 3.1
n Take samples of  iron, copper, aluminium and magnesium. Note
the appearance of each sample.
n Clean the surface of each sample by rubbing them with sand paper
and note their appearance again.
Metals, in their pure state, have a shining surface. This property is
called metallic lustre.
Activity 3.2 Activity 3.2 Activity 3.2 Activity 3.2 Activity 3.2
n Take small pieces of iron, copper, aluminium, and magnesium.
Try to cut these metals with a sharp knife and note your
observations.
n Hold a piece of sodium metal with a pair of tongs.
CAUTION: Always handle sodium metal with care. Dry it by
pressing between the folds of a filter paper.
n Put it on a watch-glass and try to cut it with a knife.
n What do you observe?
2024-25
Science
38
You will find that some metals can be beaten into thin sheets. This
property is called malleability. Did you know that gold and silver are the
most malleable metals?
Activity 3.3 Activity 3.3 Activity 3.3 Activity 3.3 Activity 3.3
n Take pieces of iron, zinc, lead and copper.
n Place any one metal on a block of iron and strike it four or five
times with a hammer. What do you observe?
n Repeat with other metals.
n Record the change in the shape of these metals.
You will find that metals are generally hard. The hardness varies
from metal to metal.
Activity 3.4 Activity 3.4 Activity 3.4 Activity 3.4 Activity 3.4
n List the metals whose wires you have seen in daily life.
The ability of metals to be drawn into thin wires is called ductility.
Gold is the most ductile metal. You will be surprised to know that a wire
of about 2 km length can be drawn from one gram of gold.
It is because of their malleability and ductility that metals can be
given different shapes according to our needs.
Can you name some metals that are used for making cooking vessels?
Do you know why these metals are used for making vessels? Let us do
the following Activity to find out the answer.
Activity 3.5 Activity 3.5 Activity 3.5 Activity 3.5 Activity 3.5
n Take an aluminium or copper
wire. Clamp this wire on a
stand, as shown in Fig. 3.1.
n Fix a pin to the free end of the
wire using wax.
n Heat the wire with a spirit lamp,
candle or a burner near the
place where it is clamped.
n What do you observe after some
time?
n Note your observations. Does
the metal wire melt?
The above activity shows that metals are good conductors of heat
and have high melting points. The best conductors of heat are silver and
copper. Lead and mercury are comparatively poor conductors of heat.
Do metals also conduct electricity? Let us find out.
Figure 3.1 Figure 3.1 Figure 3.1 Figure 3.1 Figure 3.1
Metals are good
conductors of heat.
2024-25
Page 3


Metals and Non-metals
3 CHAPTER
I
n Class IX you have learnt about various elements. You have seen
that elements can be classified as metals or non-metals on the basis of
their properties.
n Think of some uses of metals and non-metals in your daily life.
n What properties did you think of while categorising elements
as metals or non-metals?
n How are these properties related to the uses of these elements?
Let us look at some of these properties in detail.
3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSICAL PROPERTIES AL PROPERTIES AL PROPERTIES AL PROPERTIES AL PROPERTIES
3.1.1 Metals
The easiest way to start grouping substances is by comparing their
physical properties. Let us study this with the help of the following
activities. For performing Activities 3.1 to 3.6, collect the samples of
following metals – iron, copper, aluminium, magnesium, sodium, lead,
zinc and any other metal that is easily available.
Activity 3.1 Activity 3.1 Activity 3.1 Activity 3.1 Activity 3.1
n Take samples of  iron, copper, aluminium and magnesium. Note
the appearance of each sample.
n Clean the surface of each sample by rubbing them with sand paper
and note their appearance again.
Metals, in their pure state, have a shining surface. This property is
called metallic lustre.
Activity 3.2 Activity 3.2 Activity 3.2 Activity 3.2 Activity 3.2
n Take small pieces of iron, copper, aluminium, and magnesium.
Try to cut these metals with a sharp knife and note your
observations.
n Hold a piece of sodium metal with a pair of tongs.
CAUTION: Always handle sodium metal with care. Dry it by
pressing between the folds of a filter paper.
n Put it on a watch-glass and try to cut it with a knife.
n What do you observe?
2024-25
Science
38
You will find that some metals can be beaten into thin sheets. This
property is called malleability. Did you know that gold and silver are the
most malleable metals?
Activity 3.3 Activity 3.3 Activity 3.3 Activity 3.3 Activity 3.3
n Take pieces of iron, zinc, lead and copper.
n Place any one metal on a block of iron and strike it four or five
times with a hammer. What do you observe?
n Repeat with other metals.
n Record the change in the shape of these metals.
You will find that metals are generally hard. The hardness varies
from metal to metal.
Activity 3.4 Activity 3.4 Activity 3.4 Activity 3.4 Activity 3.4
n List the metals whose wires you have seen in daily life.
The ability of metals to be drawn into thin wires is called ductility.
Gold is the most ductile metal. You will be surprised to know that a wire
of about 2 km length can be drawn from one gram of gold.
It is because of their malleability and ductility that metals can be
given different shapes according to our needs.
Can you name some metals that are used for making cooking vessels?
Do you know why these metals are used for making vessels? Let us do
the following Activity to find out the answer.
Activity 3.5 Activity 3.5 Activity 3.5 Activity 3.5 Activity 3.5
n Take an aluminium or copper
wire. Clamp this wire on a
stand, as shown in Fig. 3.1.
n Fix a pin to the free end of the
wire using wax.
n Heat the wire with a spirit lamp,
candle or a burner near the
place where it is clamped.
n What do you observe after some
time?
n Note your observations. Does
the metal wire melt?
The above activity shows that metals are good conductors of heat
and have high melting points. The best conductors of heat are silver and
copper. Lead and mercury are comparatively poor conductors of heat.
Do metals also conduct electricity? Let us find out.
Figure 3.1 Figure 3.1 Figure 3.1 Figure 3.1 Figure 3.1
Metals are good
conductors of heat.
2024-25
Metals and Non-metals 39
You must have seen that the wires that carry current
in your homes have a coating of polyvinylchloride (PVC)
or a rubber-like material. Why are electric wires coated
with such substances?
What happens when metals strike a hard surface? Do they produce
a sound? The metals that produce a sound on striking a hard surface
are said to be sonorous. Can you now say why school bells are made of
metals?
3.1.2 Non-metals
In the previous Class you have learnt that there are very few non-metals
as compared to metals. Some of the examples of non-metals are carbon,
sulphur, iodine, oxygen, hydrogen, etc. The non-metals are either  solids
or gases except bromine which is a liquid.
Do non-metals also have physical properties similar to that of metals?
Let us find out.
Activity 3.6 Activity 3.6 Activity 3.6 Activity 3.6 Activity 3.6
n Set up an electric circuit as shown in Fig. 3.2.
n Place the metal to be tested in the circuit
between terminals A and B as shown.
n Does the bulb glow? What does this indicate?
Figure 3.2 Figure 3.2 Figure 3.2 Figure 3.2 Figure 3.2
Metals are good
conductors of electricity.
Activity 3.7 Activity 3.7 Activity 3.7 Activity 3.7 Activity 3.7
n Collect samples of carbon (coal or graphite), sulphur and iodine.
n Carry out the Activities 3.1 to 3.4 and 3.6 with these non-metals
and record your observations.
Compile your observations regarding metals and non-metals in Table 3.1.
Table 3.1
Element Symbol Type of Hardness Malleability Ductility Conducts Sonority
surface Electricity
On the bases of the observations recorded in Table 3.1, discuss the
general physical properties of metals and non-metals in the class. You
must have concluded that we cannot group elements according to their
physical properties alone, as there are many exceptions. For example –
(i) All metals except mercury exist as solids at room temperature.
In Activity 3.5, you have observed that metals have high melting
2024-25
Page 4


Metals and Non-metals
3 CHAPTER
I
n Class IX you have learnt about various elements. You have seen
that elements can be classified as metals or non-metals on the basis of
their properties.
n Think of some uses of metals and non-metals in your daily life.
n What properties did you think of while categorising elements
as metals or non-metals?
n How are these properties related to the uses of these elements?
Let us look at some of these properties in detail.
3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSICAL PROPERTIES AL PROPERTIES AL PROPERTIES AL PROPERTIES AL PROPERTIES
3.1.1 Metals
The easiest way to start grouping substances is by comparing their
physical properties. Let us study this with the help of the following
activities. For performing Activities 3.1 to 3.6, collect the samples of
following metals – iron, copper, aluminium, magnesium, sodium, lead,
zinc and any other metal that is easily available.
Activity 3.1 Activity 3.1 Activity 3.1 Activity 3.1 Activity 3.1
n Take samples of  iron, copper, aluminium and magnesium. Note
the appearance of each sample.
n Clean the surface of each sample by rubbing them with sand paper
and note their appearance again.
Metals, in their pure state, have a shining surface. This property is
called metallic lustre.
Activity 3.2 Activity 3.2 Activity 3.2 Activity 3.2 Activity 3.2
n Take small pieces of iron, copper, aluminium, and magnesium.
Try to cut these metals with a sharp knife and note your
observations.
n Hold a piece of sodium metal with a pair of tongs.
CAUTION: Always handle sodium metal with care. Dry it by
pressing between the folds of a filter paper.
n Put it on a watch-glass and try to cut it with a knife.
n What do you observe?
2024-25
Science
38
You will find that some metals can be beaten into thin sheets. This
property is called malleability. Did you know that gold and silver are the
most malleable metals?
Activity 3.3 Activity 3.3 Activity 3.3 Activity 3.3 Activity 3.3
n Take pieces of iron, zinc, lead and copper.
n Place any one metal on a block of iron and strike it four or five
times with a hammer. What do you observe?
n Repeat with other metals.
n Record the change in the shape of these metals.
You will find that metals are generally hard. The hardness varies
from metal to metal.
Activity 3.4 Activity 3.4 Activity 3.4 Activity 3.4 Activity 3.4
n List the metals whose wires you have seen in daily life.
The ability of metals to be drawn into thin wires is called ductility.
Gold is the most ductile metal. You will be surprised to know that a wire
of about 2 km length can be drawn from one gram of gold.
It is because of their malleability and ductility that metals can be
given different shapes according to our needs.
Can you name some metals that are used for making cooking vessels?
Do you know why these metals are used for making vessels? Let us do
the following Activity to find out the answer.
Activity 3.5 Activity 3.5 Activity 3.5 Activity 3.5 Activity 3.5
n Take an aluminium or copper
wire. Clamp this wire on a
stand, as shown in Fig. 3.1.
n Fix a pin to the free end of the
wire using wax.
n Heat the wire with a spirit lamp,
candle or a burner near the
place where it is clamped.
n What do you observe after some
time?
n Note your observations. Does
the metal wire melt?
The above activity shows that metals are good conductors of heat
and have high melting points. The best conductors of heat are silver and
copper. Lead and mercury are comparatively poor conductors of heat.
Do metals also conduct electricity? Let us find out.
Figure 3.1 Figure 3.1 Figure 3.1 Figure 3.1 Figure 3.1
Metals are good
conductors of heat.
2024-25
Metals and Non-metals 39
You must have seen that the wires that carry current
in your homes have a coating of polyvinylchloride (PVC)
or a rubber-like material. Why are electric wires coated
with such substances?
What happens when metals strike a hard surface? Do they produce
a sound? The metals that produce a sound on striking a hard surface
are said to be sonorous. Can you now say why school bells are made of
metals?
3.1.2 Non-metals
In the previous Class you have learnt that there are very few non-metals
as compared to metals. Some of the examples of non-metals are carbon,
sulphur, iodine, oxygen, hydrogen, etc. The non-metals are either  solids
or gases except bromine which is a liquid.
Do non-metals also have physical properties similar to that of metals?
Let us find out.
Activity 3.6 Activity 3.6 Activity 3.6 Activity 3.6 Activity 3.6
n Set up an electric circuit as shown in Fig. 3.2.
n Place the metal to be tested in the circuit
between terminals A and B as shown.
n Does the bulb glow? What does this indicate?
Figure 3.2 Figure 3.2 Figure 3.2 Figure 3.2 Figure 3.2
Metals are good
conductors of electricity.
Activity 3.7 Activity 3.7 Activity 3.7 Activity 3.7 Activity 3.7
n Collect samples of carbon (coal or graphite), sulphur and iodine.
n Carry out the Activities 3.1 to 3.4 and 3.6 with these non-metals
and record your observations.
Compile your observations regarding metals and non-metals in Table 3.1.
Table 3.1
Element Symbol Type of Hardness Malleability Ductility Conducts Sonority
surface Electricity
On the bases of the observations recorded in Table 3.1, discuss the
general physical properties of metals and non-metals in the class. You
must have concluded that we cannot group elements according to their
physical properties alone, as there are many exceptions. For example –
(i) All metals except mercury exist as solids at room temperature.
In Activity 3.5, you have observed that metals have high melting
2024-25
Science
40
points but gallium and caesium have very low melting points.
These two metals will melt if you keep them on your palm.
(ii) Iodine is a non-metal but it is lustrous.
(iii) Carbon is a non-metal that can exist in different forms. Each
form is called an allotrope. Diamond, an allotrope of carbon, is
the hardest natural substance known and has a very high melting
and boiling point. Graphite, another allotrope of carbon, is a
conductor of electricity.
(iv) Alkali metals (lithium, sodium, potassium) are so soft that they
can be cut with a knife. They have low densities and low melting
points.
Elements can be more clearly classified as metals and non-metals
on the basis of their chemical properties.
Activity 3.8 Activity 3.8 Activity 3.8 Activity 3.8 Activity 3.8
n Take a magnesium ribbon and some sulphur powder.
n Burn the magnesium ribbon. Collect the ashes formed and dissolve
them in water.
n Test the resultant solution with both red and blue litmus paper.
n Is the product formed on burning magnesium acidic or basic?
n Now burn sulphur powder. Place a test tube over the burning
sulphur to collect the fumes produced.
n Add some water to the above test tube and shake.
n Test this solution with blue and red litmus paper.
n Is the product formed on burning sulphur acidic or basic?
n Can you write equations for these reactions?
QUESTIONS
?
1. Give an example of a metal which
(i) is a liquid at room temperature.
(ii) can be easily cut with a knife.
(iii) is the best conductor of heat.
(iv) is a poor conductor of heat.
2. Explain the meanings of malleable and ductile.
3.2 CHEMIC 3.2 CHEMIC 3.2 CHEMIC 3.2 CHEMIC 3.2 CHEMICAL PROPERTIES OF MET AL PROPERTIES OF MET AL PROPERTIES OF MET AL PROPERTIES OF MET AL PROPERTIES OF METALS ALS ALS ALS ALS
We will learn about the chemical properties of metals in the following
Sections 3.2.1 to 3.2.4. For this, collect the samples of following metals –
aluminium, copper, iron, lead, magnesium, zinc and sodium.
 Most non-metals produce acidic oxides when dissolve in water. On
the other hand, most metals, give rise to basic oxides. You will be learning
more about these metal oxides in the next section.
2024-25
Page 5


Metals and Non-metals
3 CHAPTER
I
n Class IX you have learnt about various elements. You have seen
that elements can be classified as metals or non-metals on the basis of
their properties.
n Think of some uses of metals and non-metals in your daily life.
n What properties did you think of while categorising elements
as metals or non-metals?
n How are these properties related to the uses of these elements?
Let us look at some of these properties in detail.
3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSIC 3.1 PHYSICAL PROPERTIES AL PROPERTIES AL PROPERTIES AL PROPERTIES AL PROPERTIES
3.1.1 Metals
The easiest way to start grouping substances is by comparing their
physical properties. Let us study this with the help of the following
activities. For performing Activities 3.1 to 3.6, collect the samples of
following metals – iron, copper, aluminium, magnesium, sodium, lead,
zinc and any other metal that is easily available.
Activity 3.1 Activity 3.1 Activity 3.1 Activity 3.1 Activity 3.1
n Take samples of  iron, copper, aluminium and magnesium. Note
the appearance of each sample.
n Clean the surface of each sample by rubbing them with sand paper
and note their appearance again.
Metals, in their pure state, have a shining surface. This property is
called metallic lustre.
Activity 3.2 Activity 3.2 Activity 3.2 Activity 3.2 Activity 3.2
n Take small pieces of iron, copper, aluminium, and magnesium.
Try to cut these metals with a sharp knife and note your
observations.
n Hold a piece of sodium metal with a pair of tongs.
CAUTION: Always handle sodium metal with care. Dry it by
pressing between the folds of a filter paper.
n Put it on a watch-glass and try to cut it with a knife.
n What do you observe?
2024-25
Science
38
You will find that some metals can be beaten into thin sheets. This
property is called malleability. Did you know that gold and silver are the
most malleable metals?
Activity 3.3 Activity 3.3 Activity 3.3 Activity 3.3 Activity 3.3
n Take pieces of iron, zinc, lead and copper.
n Place any one metal on a block of iron and strike it four or five
times with a hammer. What do you observe?
n Repeat with other metals.
n Record the change in the shape of these metals.
You will find that metals are generally hard. The hardness varies
from metal to metal.
Activity 3.4 Activity 3.4 Activity 3.4 Activity 3.4 Activity 3.4
n List the metals whose wires you have seen in daily life.
The ability of metals to be drawn into thin wires is called ductility.
Gold is the most ductile metal. You will be surprised to know that a wire
of about 2 km length can be drawn from one gram of gold.
It is because of their malleability and ductility that metals can be
given different shapes according to our needs.
Can you name some metals that are used for making cooking vessels?
Do you know why these metals are used for making vessels? Let us do
the following Activity to find out the answer.
Activity 3.5 Activity 3.5 Activity 3.5 Activity 3.5 Activity 3.5
n Take an aluminium or copper
wire. Clamp this wire on a
stand, as shown in Fig. 3.1.
n Fix a pin to the free end of the
wire using wax.
n Heat the wire with a spirit lamp,
candle or a burner near the
place where it is clamped.
n What do you observe after some
time?
n Note your observations. Does
the metal wire melt?
The above activity shows that metals are good conductors of heat
and have high melting points. The best conductors of heat are silver and
copper. Lead and mercury are comparatively poor conductors of heat.
Do metals also conduct electricity? Let us find out.
Figure 3.1 Figure 3.1 Figure 3.1 Figure 3.1 Figure 3.1
Metals are good
conductors of heat.
2024-25
Metals and Non-metals 39
You must have seen that the wires that carry current
in your homes have a coating of polyvinylchloride (PVC)
or a rubber-like material. Why are electric wires coated
with such substances?
What happens when metals strike a hard surface? Do they produce
a sound? The metals that produce a sound on striking a hard surface
are said to be sonorous. Can you now say why school bells are made of
metals?
3.1.2 Non-metals
In the previous Class you have learnt that there are very few non-metals
as compared to metals. Some of the examples of non-metals are carbon,
sulphur, iodine, oxygen, hydrogen, etc. The non-metals are either  solids
or gases except bromine which is a liquid.
Do non-metals also have physical properties similar to that of metals?
Let us find out.
Activity 3.6 Activity 3.6 Activity 3.6 Activity 3.6 Activity 3.6
n Set up an electric circuit as shown in Fig. 3.2.
n Place the metal to be tested in the circuit
between terminals A and B as shown.
n Does the bulb glow? What does this indicate?
Figure 3.2 Figure 3.2 Figure 3.2 Figure 3.2 Figure 3.2
Metals are good
conductors of electricity.
Activity 3.7 Activity 3.7 Activity 3.7 Activity 3.7 Activity 3.7
n Collect samples of carbon (coal or graphite), sulphur and iodine.
n Carry out the Activities 3.1 to 3.4 and 3.6 with these non-metals
and record your observations.
Compile your observations regarding metals and non-metals in Table 3.1.
Table 3.1
Element Symbol Type of Hardness Malleability Ductility Conducts Sonority
surface Electricity
On the bases of the observations recorded in Table 3.1, discuss the
general physical properties of metals and non-metals in the class. You
must have concluded that we cannot group elements according to their
physical properties alone, as there are many exceptions. For example –
(i) All metals except mercury exist as solids at room temperature.
In Activity 3.5, you have observed that metals have high melting
2024-25
Science
40
points but gallium and caesium have very low melting points.
These two metals will melt if you keep them on your palm.
(ii) Iodine is a non-metal but it is lustrous.
(iii) Carbon is a non-metal that can exist in different forms. Each
form is called an allotrope. Diamond, an allotrope of carbon, is
the hardest natural substance known and has a very high melting
and boiling point. Graphite, another allotrope of carbon, is a
conductor of electricity.
(iv) Alkali metals (lithium, sodium, potassium) are so soft that they
can be cut with a knife. They have low densities and low melting
points.
Elements can be more clearly classified as metals and non-metals
on the basis of their chemical properties.
Activity 3.8 Activity 3.8 Activity 3.8 Activity 3.8 Activity 3.8
n Take a magnesium ribbon and some sulphur powder.
n Burn the magnesium ribbon. Collect the ashes formed and dissolve
them in water.
n Test the resultant solution with both red and blue litmus paper.
n Is the product formed on burning magnesium acidic or basic?
n Now burn sulphur powder. Place a test tube over the burning
sulphur to collect the fumes produced.
n Add some water to the above test tube and shake.
n Test this solution with blue and red litmus paper.
n Is the product formed on burning sulphur acidic or basic?
n Can you write equations for these reactions?
QUESTIONS
?
1. Give an example of a metal which
(i) is a liquid at room temperature.
(ii) can be easily cut with a knife.
(iii) is the best conductor of heat.
(iv) is a poor conductor of heat.
2. Explain the meanings of malleable and ductile.
3.2 CHEMIC 3.2 CHEMIC 3.2 CHEMIC 3.2 CHEMIC 3.2 CHEMICAL PROPERTIES OF MET AL PROPERTIES OF MET AL PROPERTIES OF MET AL PROPERTIES OF MET AL PROPERTIES OF METALS ALS ALS ALS ALS
We will learn about the chemical properties of metals in the following
Sections 3.2.1 to 3.2.4. For this, collect the samples of following metals –
aluminium, copper, iron, lead, magnesium, zinc and sodium.
 Most non-metals produce acidic oxides when dissolve in water. On
the other hand, most metals, give rise to basic oxides. You will be learning
more about these metal oxides in the next section.
2024-25
Metals and Non-metals 41
3.2.1 What happens when Metals are burnt in Air?
You have seen in Activity 3.8 that magnesium burns in air with a dazzling
white flame. Do all metals react in the same manner? Let us check by
performing the following Activity.
Activity 3.9 Activity 3.9 Activity 3.9 Activity 3.9 Activity 3.9
CAUTION: The following activity needs the teacher’s assistance.
It would be better if students wear eye protection.
n Hold any of the samples taken above with a pair of tongs and try
burning over a flame. Repeat with the other metal samples.
n Collect the product if formed.
n Let the products and the metal surface cool down.
n Which metals burn easily?
n What flame colour did you observe when the metal burnt?
n How does the metal surface appear after burning?
n Arrange the metals in the decreasing order of their reactivity
towards oxygen.
n Are the products soluble in water?
Almost all metals combine with oxygen to form metal oxides.
Metal  +  Oxygen ? Metal oxide
 For example, when copper is heated in air, it combines with oxygen
to form copper(II) oxide, a black oxide.
2Cu  +  O
2
  ?  2CuO
(Copper)     (Copper(II) oxide)
Similarly, aluminium forms aluminium oxide.
4Al + 3O
2
 ? 2Al
2
O
3
(Aluminium) (Aluminium oxide)
Recall from Chapter 2, how copper oxide reacts with hydrochloric acid.
We have learnt that metal oxides are basic in nature. But some metal
oxides, such as aluminium oxide, zinc oxide show both acidic as well as
basic behaviour. Such metal oxides which react with both acids as well as
bases to produce salts and water are known as amphoteric oxides.
Aluminium oxide reacts in the following manner with acids and bases –
Al
2
O
3
 + 6HCl ? 2AlCl
3
+ 3H
2
O
Al
2
O
3
 + 2NaOH ? 2NaAlO
2
+ H
2
O
(Sodium
aluminate)
 Most metal oxides are insoluble in water but some of these dissolve
in water to form alkalis. Sodium oxide and potassium oxide dissolve in
water to produce alkalis as follows –
Na
2
O(s) + H
2
O(l) ? 2NaOH(aq)
K
2
O(s) + H
2
O(l) ? 2KOH(aq)
2024-25