Chapter 4 Materials: Metals and Non-metals Class 8 Notes | EduRev

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Class 8 : Chapter 4 Materials: Metals and Non-metals Class 8 Notes | EduRev

 Page 1


Chapter 4 Materials: Metals and Non-Metals 
Matter – Anything that occupies space and has mass is called matter.  
Three main types of matter – Solid, Liquid and Gas 
Atoms – The smallest unit (constituent particle) of matter. 
Elements – the purest form of matter made of single type of atoms. E.g. Iron, Zinc, Copper, Oxygen, Carbon 
etc. 
Name of some important elements and their symbols: 
1. Hydrogen     H 
2. Carbon      C 
3. Oxygen     O 
4. Magnesium     Mg 
5. Chlorine     Cl 
6. Iron      Fe 
7. Copper      Cu 
 
Metals and Non -Metals 
E.g. of metals – Sodium (Na), Magnesium (Mg), Aluminium (Al), Iron (Fe), Copper (Cu), Zinc (Zn), etc.  
E.g. of Non-metals – Oxygen (O), Nitrogen (N), Phosphorus (P), Chlorine (Cl) etc.  
Properties of metals and Non-metals:  
1. Physical properties: 
 
a) Hardness – All metals except mercury are solid and hard at room temperature (24
0
C). Non-metals 
may or may not be hard. They can be gaseous, powdery or solid. 
b) Conductors – Metals are good conductor of heat and electricity. Heat and electricity can pass 
through metals, although not all metals conduct at the same rate. Non-metals do not conduct heat and 
electricity. 
c) Malleable – Metals can be beaten into thin sheets and this property of metals is called malleability. 
Non-metals are not malleable and becomes powdery when beaten. 
d) Sonorous – Metals produce a ringing sound when hit. Non-metals are not sonorous 
e) Ductile – the property of metals to be drawn into wires is known as ductility. Non metals are not 
ductile. 
 
2. Chemical properties 
Ions – Charged molecules are called ions. The molecules can contain a positive or a negative charge.  
The positively charged ions are called cations e.g. hydrogen and negatively charged ions are called anions 
example negatively charged chlorine ion and hydroxide ions. 
Litmus paper – a special piece of paper strip, which turns red when kept in an acidic solution and blue when 
kept in a basic solution. 
Page 2


Chapter 4 Materials: Metals and Non-Metals 
Matter – Anything that occupies space and has mass is called matter.  
Three main types of matter – Solid, Liquid and Gas 
Atoms – The smallest unit (constituent particle) of matter. 
Elements – the purest form of matter made of single type of atoms. E.g. Iron, Zinc, Copper, Oxygen, Carbon 
etc. 
Name of some important elements and their symbols: 
1. Hydrogen     H 
2. Carbon      C 
3. Oxygen     O 
4. Magnesium     Mg 
5. Chlorine     Cl 
6. Iron      Fe 
7. Copper      Cu 
 
Metals and Non -Metals 
E.g. of metals – Sodium (Na), Magnesium (Mg), Aluminium (Al), Iron (Fe), Copper (Cu), Zinc (Zn), etc.  
E.g. of Non-metals – Oxygen (O), Nitrogen (N), Phosphorus (P), Chlorine (Cl) etc.  
Properties of metals and Non-metals:  
1. Physical properties: 
 
a) Hardness – All metals except mercury are solid and hard at room temperature (24
0
C). Non-metals 
may or may not be hard. They can be gaseous, powdery or solid. 
b) Conductors – Metals are good conductor of heat and electricity. Heat and electricity can pass 
through metals, although not all metals conduct at the same rate. Non-metals do not conduct heat and 
electricity. 
c) Malleable – Metals can be beaten into thin sheets and this property of metals is called malleability. 
Non-metals are not malleable and becomes powdery when beaten. 
d) Sonorous – Metals produce a ringing sound when hit. Non-metals are not sonorous 
e) Ductile – the property of metals to be drawn into wires is known as ductility. Non metals are not 
ductile. 
 
2. Chemical properties 
Ions – Charged molecules are called ions. The molecules can contain a positive or a negative charge.  
The positively charged ions are called cations e.g. hydrogen and negatively charged ions are called anions 
example negatively charged chlorine ion and hydroxide ions. 
Litmus paper – a special piece of paper strip, which turns red when kept in an acidic solution and blue when 
kept in a basic solution. 
Acids – Substances that release hydrogen ions and turn blue litmus paper to red.  
Base – Substances that release hydroxide ions and turns red litmus paper to blue. 
 
1. Reaction with Oxygen 
a. Metals 
Metals react with oxygen to form basic oxides 
E.g. 
i)  Mg         +     O2            MgO 
 (Magnesium)      (Oxygen)   (Magnesium oxide) 
Magnesium reacts with oxygen to produce magnesium oxide. 
ii)         Fe   +    O2   +   H2O      Fe2O3   
  (Iron) (Oxygen) (Water)   (Iron oxide) 
        Iron reacts with oxygen and water to form rust. 
 
iii)  Na +    O2        Na2O 
       (Sodium)   (Oxygen)   (Sodium oxide) 
        Sodium is very reactive and catches fire when exposed to air (oxygen). 
 
When these oxides are dissolved in water by bringing a test tube containing water near the flames of a 
burning metal and a red litmus paper is dipped in the water, it will turn blue, indicating the basic nature 
of the metal oxides. 
 
b. Non-metals 
Non-metals react with oxygen to form acidic oxides. 
E.g. Sulphur reacts with oxygen to produce sulphur dioxide 
   Nitrogen reacts with oxygen to produce nitrogen dioxide. 
When a blue litmus paper is dipped in water containing non-metal oxides, it will turn red indicating 
the acidic nature of the non-metallic oxides. 
Phosphorus is a very reactive non-metal and catches fire when exposed to air (oxygen). 
 
2. Reaction with water 
a. Metals 
Some metals such as sodium reacts vigorously with water to catch fire while others such as iron and 
copper reacts very slowly. 
b. Non-metals 
Non-metals generally do not react with water but phosphorus is a very reactive non-metal and 
catches fire when exposed to water. 
 
Both sodium (a metal) and phosphorus (a non-metal) reacts vigorously with oxygen and water to 
catch fire, so are stored in kerosene. 
 
3. Reaction with acids 
a. Metals  
Metals react with acids to produce hydrogen gas, which can be identified by bringing a matchstick on 
the mouth of the test tube as hydrogen burns with a “pop” sound. 
Page 3


Chapter 4 Materials: Metals and Non-Metals 
Matter – Anything that occupies space and has mass is called matter.  
Three main types of matter – Solid, Liquid and Gas 
Atoms – The smallest unit (constituent particle) of matter. 
Elements – the purest form of matter made of single type of atoms. E.g. Iron, Zinc, Copper, Oxygen, Carbon 
etc. 
Name of some important elements and their symbols: 
1. Hydrogen     H 
2. Carbon      C 
3. Oxygen     O 
4. Magnesium     Mg 
5. Chlorine     Cl 
6. Iron      Fe 
7. Copper      Cu 
 
Metals and Non -Metals 
E.g. of metals – Sodium (Na), Magnesium (Mg), Aluminium (Al), Iron (Fe), Copper (Cu), Zinc (Zn), etc.  
E.g. of Non-metals – Oxygen (O), Nitrogen (N), Phosphorus (P), Chlorine (Cl) etc.  
Properties of metals and Non-metals:  
1. Physical properties: 
 
a) Hardness – All metals except mercury are solid and hard at room temperature (24
0
C). Non-metals 
may or may not be hard. They can be gaseous, powdery or solid. 
b) Conductors – Metals are good conductor of heat and electricity. Heat and electricity can pass 
through metals, although not all metals conduct at the same rate. Non-metals do not conduct heat and 
electricity. 
c) Malleable – Metals can be beaten into thin sheets and this property of metals is called malleability. 
Non-metals are not malleable and becomes powdery when beaten. 
d) Sonorous – Metals produce a ringing sound when hit. Non-metals are not sonorous 
e) Ductile – the property of metals to be drawn into wires is known as ductility. Non metals are not 
ductile. 
 
2. Chemical properties 
Ions – Charged molecules are called ions. The molecules can contain a positive or a negative charge.  
The positively charged ions are called cations e.g. hydrogen and negatively charged ions are called anions 
example negatively charged chlorine ion and hydroxide ions. 
Litmus paper – a special piece of paper strip, which turns red when kept in an acidic solution and blue when 
kept in a basic solution. 
Acids – Substances that release hydrogen ions and turn blue litmus paper to red.  
Base – Substances that release hydroxide ions and turns red litmus paper to blue. 
 
1. Reaction with Oxygen 
a. Metals 
Metals react with oxygen to form basic oxides 
E.g. 
i)  Mg         +     O2            MgO 
 (Magnesium)      (Oxygen)   (Magnesium oxide) 
Magnesium reacts with oxygen to produce magnesium oxide. 
ii)         Fe   +    O2   +   H2O      Fe2O3   
  (Iron) (Oxygen) (Water)   (Iron oxide) 
        Iron reacts with oxygen and water to form rust. 
 
iii)  Na +    O2        Na2O 
       (Sodium)   (Oxygen)   (Sodium oxide) 
        Sodium is very reactive and catches fire when exposed to air (oxygen). 
 
When these oxides are dissolved in water by bringing a test tube containing water near the flames of a 
burning metal and a red litmus paper is dipped in the water, it will turn blue, indicating the basic nature 
of the metal oxides. 
 
b. Non-metals 
Non-metals react with oxygen to form acidic oxides. 
E.g. Sulphur reacts with oxygen to produce sulphur dioxide 
   Nitrogen reacts with oxygen to produce nitrogen dioxide. 
When a blue litmus paper is dipped in water containing non-metal oxides, it will turn red indicating 
the acidic nature of the non-metallic oxides. 
Phosphorus is a very reactive non-metal and catches fire when exposed to air (oxygen). 
 
2. Reaction with water 
a. Metals 
Some metals such as sodium reacts vigorously with water to catch fire while others such as iron and 
copper reacts very slowly. 
b. Non-metals 
Non-metals generally do not react with water but phosphorus is a very reactive non-metal and 
catches fire when exposed to water. 
 
Both sodium (a metal) and phosphorus (a non-metal) reacts vigorously with oxygen and water to 
catch fire, so are stored in kerosene. 
 
3. Reaction with acids 
a. Metals  
Metals react with acids to produce hydrogen gas, which can be identified by bringing a matchstick on 
the mouth of the test tube as hydrogen burns with a “pop” sound. 
However, copper is a less reactive metal and does not react with dilute hydrochloric acid but reacts with 
sulphuric acid. 
b. Non-metals 
Non-metals generally do not react with acids. 
 
4. Reactions with bases 
a. Metals 
Metals react with bases with a “pop” sound indicating the release of hydrogen gas. 
b. Non-metals 
The reaction of non-metals with bases are complex and will be discussed in higher classes. 
 
5. Displacement reactions 
 
A type of reaction in which a more reactive element displaces a less reactive element from its salt 
solution is known as displacement reactions. 
 
Magnesium is more reactive than Zinc, which is more reactive than iron and iron is more reactive than 
copper 
Or  
Magnesium (Mg) > Zinc (Zn) > Iron (Fe) > copper (Cu) 
 
Examples of displacement reactions 
1. Copper sulphate (CuSo4) + Iron (Fe)     Iron sulphate (FeSO4) + Copper (Cu) 
 (Blue)                                                           (Green) 
 
Iron sulphate (FeSO4) + Copper (Cu)       No reaction (because copper is less reactive than iron and 
cannot displace iron from its salt solution) 
 
2. Magnesium (Mg) + Iron sulphate (FeSO 4)   Magnesium Sulphate (MgSO4) + Iron (Fe) 
Magnesium Sulphate (MgSO4) + Iron (Fe)     No reaction (because iron is less reactive than magnesium 
and cannot displace magnesium from its salt solution) 
Uses of Metals 
1. Metals are used in making utensils, vehicles, bridges, machinery and industrial gadgets. 
2. Metals such as sodium and iron are essential components of our diet. 
3. Copper is used to make wires, which are used to conduct electricity in our homes. 
4. Gold and silver are used in making jewelry. 
Uses of Non-metals 
1. Oxygen is essential for breathing and survival of organisms on Earth. 
2. Non-metals such as phosphorus, sulphur and nitrogen are used in the fertilizers. 
3. Chlorine is used in the treatment of water. 
4. Non-metals are used in crackers and match sticks. 
5. Chlorine and iodine forms an essential part of a balanced diet. 
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