Some materials are hard, lustrous, malleable, ductile, sonorous and good conductors of heat and electricity. The materials which generally posses these properties are called metals. The examples of metals are iron, copper, aluminium, calcium, magnesium, etc.
In contrast, materials like coal and sulphur are soft and dull in appearance. They break down into powdery mass on tapping with hammer.They are not sonorous and are poor conductors of heat and electricity. These materials are called non-metals. The examples of non-metals are sulphur, carbon, oxygen, phosphorus, etc.
Metals can be distinguished from non-metals on the basis of their physical and chemical properties.
Physical Properties of Metals and Non-metals
1. Malleability: The property of metals by which they can be beaten into thin sheets is called malleability. This is a characteristic property of metals. Non-metals does not exhibit this property.
2. Ductility: The property of metal by which it can be drawn into wires is called ductility. E.g. Aluminium and copper wires can be drawn into wire. Non-metals does not exhibit this property.
3. Conduction of heat and electricity: metals are good conductors of heat and electricity. Iron rod, nail and copper wire are good conductors while rolled sulphur piece and coal piece are
poor conductors.Non-metals are poor conductor of heat and electricity.
4. Sonorous: The things made of metals produce ringing sound when struck hard.Since metals produce ringing sounds, they are said to be sonorous. The materials other than metals are not sonorous. Non-metals does not exhibit this property.
Notes: Metals like sodium and potassium are soft and can be cut with a knife. Mercury is the only metal which is found in liquid state at room temperature. These are exceptions.
Chemical Properties Of Metals and Non-metals
1. Reaction With Oxygen:
On burning, metals react with oxygen to produce metal oxides which are basic in nature. Non-metals react with oxygen to produce non- metallic oxides which are acidic in nature.
Example of reaction of metal with oxygen:
Iron (Fe) + Oxygen
(O2) + Water (H2O) à Iron
oxide (Fe2O3) (Rust)
Magnesium (Mg) + Oxygen (O2) à Magnesium oxide (MgO)
Does copper also get rusted ?
When a copper vessel is exposed to moist air for long, it acquires a dull green coating. The green material is a mixture of copper hydroxide (Cu(OH)2) and copper carbonate (CuCO3). The following is the reaction: 2Cu+H2O+CO2+O2 à Cu (OH)2 + CuCO3
Example of reaction of non- metal with oxygen:
Sulphur dioxide (SO2) + Water (H2O)
→ Sulphurous acid (H2SO3)
2. Reaction with water:
Some metals react with water to produce metal hydroxides and hydrogen gas. Generally, non metals do not react with water.
Sodium metal is very reactive. It reacts vigorously with oxygen and water. A lot of heat is generated in the reaction. It is, therefore, stored in kerosene.Sodium reacts vigorously with water. Some other metals do not do so. For example, iron reacts with water slowly.
Generally, non-metals do not react with water though they may be very reactive in air. Such non-metals are stored in water. For example, phosphorus is a very reactive non-metal. It catches fire if exposed to air. To prevent the contact of phosphorus with atmospheric oxygen, it is stored in water.
Note: copper does not react with dilute hydrochloric acid even on heating but it reacts with sulphuric acid.
Beaker A and B will show displacement reaction whereas Beaker C, D and E will not show displacement reaction. This happens because of same rule that
A more reactive metal can replace a less reactive metal, but a less reactive one cannot replace a more reactive metal.
Here's the reaction equation in beaker A and B:
Beaker A: Copper sulphate solution (blue) + Zinc → Zinc sulphate solution (Colorless) + Copper (Red)
Beaker B: Copper sulphate solution (blue) + Iron → Iron sulphate solution (green) + Copper (brown deposit)
Sodium metal is very reactive. It reacts vigorously with oxygen and water. A lot of heat is generated in the reaction. It is, therefore, stored in kerosene.Sodium reacts vigorously with water. Some other metals do not do so. For example, iron reacts with water slowly.
Generally, non-metals do not react with water though they may be very reactive in air. Such non-metals are stored in water. For example, phosphorus is a very reactive non-metal. It catches fire if exposed to air. To prevent the contact of phosphorus with atmospheric oxygen, it is stored in water.
3. Reactions with Acids:
Non metals generally do not react with acids but metals react with acids and produce hydrogen gas that burns with a ‘pop’ sound.Note: copper does not react with dilute hydrochloric acid even on heating but it reacts with sulphuric acid.
4. Reactions with Bases:
Metals react with sodium hydroxide to produce hydrogen gas. The ‘pop’ sound indicate the presence of hydrogen gas.Reactions of non-metals with bases are complex.5. Displacement Reactions:
A more reactive metal can replace a less reactive metal, but a less reactive one cannot replace a more reactive metal. Zinc is more reactive than Iron and Iron is more reactive than copper. That's why copper is not able to replace zinc from zinc sulphate.
Beaker A and B will show displacement reaction whereas Beaker C, D and E will not show displacement reaction. This happens because of same rule that
A more reactive metal can replace a less reactive metal, but a less reactive one cannot replace a more reactive metal.
Here's the reaction equation in beaker A and B:
Beaker A: Copper sulphate solution (blue) + Zinc → Zinc sulphate solution (Colorless) + Copper (Red)
Beaker B: Copper sulphate solution (blue) + Iron → Iron sulphate solution (green) + Copper (brown deposit)
Uses of Metals and Non metals :
Metals are used in making machinery, automobiles, aeroplanes, trains, satellites, industrial gadgets, cooking utensils, water boilers, etc. Here are some interesting examples of non-metals:- Non-metal essential for our life which all living beings inhale during breathing,
- Non-metals used in fertilisers to enhance the growth of plants,
- Non-metal used in water purification process,
- Non-metal used in the purple coloured solution which is applied on wounds as an antiseptic,
- Non-metals used in crackers.
- Magnesium is found in plants which is the central element of the chlorophyll molecule and is found in its ionic form (Mg++).
- Our body also have some metals such as Iron. Iron helps red blood cells deliver oxygen from the lungs to cells all over the body. Once the oxygen is delivered, iron then helps red blood cells carry carbon dioxide waste back to the lungs to be exhaled. Iron also plays a role in many important chemical reactions in the body.
Additional information:
If a substance cannot be broken down further by chemical reactions, by cooling, heating, or by electrolysis, it is called ‘element’. Sulphur is an element. So is iron. Carbon, too, is an element. The smallest unit of an element is atom.The atom of an element remains unaffected by physical changes in the element. For example, an atom of liquid sulphur would be exactly the same as the atom of solid or vapour sulphur.
Although we have an infinite variety of substances in the universe, the number of elements forming these substances is limited. There are no more than 118 naturally occurring elements. An important classification of elements is in terms of metals and non-metals. Most of the elements are metals. Less than 20 are non-metals.
A few are metalloids which possess characters of both metals and non-metals.
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