Metals And Non-metals

Classification of elements

The elements that are present on earth are classified as metals and non-metals on the basis of their properties. And the basis of their classification is based on the physical and chemical properties.

Physical Properties of Metals and Non-metals

Physical properties of metals

1.  Metals are solid and hard.

2.  Malleability:-

• Some metals can be beaten into thin sheets. This property is called malleability.
• Gold and silver are most malleable metals.

3.  Ductility:-

• The ability of metals to be drawn into thin wires is called ductility.
• Gold is the most ductile metal. A wire of about 2 km can be drawn from one gram of gold.

4.  Metallic lustre.

• Metals in their pure state have a shining surface. This property is called metallic lusture.
• Metals can be given different shapes according to our needs because of their malleability and ductility.

5.  Heat conduction:-

• Metals are good conductors of heat and have high melting points.
• Silver and copper are best conductors of heat.
• Lead and mercury are comparatively poor conductors of heat.

6.  Electrical conductivity:-

• Metals are good conductors of electricity.
• Silver is the best conductor of electricity. But copper is commonly used for electrical wiring because silver is much expensive than cooper.

7.  Sonorous:-

• Metal that produces sound when strikes with a hard substance are said to sonorous. Metals are sonorous in nature.

Physical properties of non-metals

1. Non-metals are either solids or gases except bromine which is a liquid.
2. They are non malleable.
3. They are non ductile.
4. They are bad conductors of heat and electricity.
5. They are non sonorous.
6. They are non lustrous.

We can’t group elements according to their physical properties alone, as there are many exceptions. For example:-

1. All metals exist as solids at room temperature except mercury.
2. Metals have high melting points but gallium and caesium have very low melting points. These two metals will melt if you keep them on your palm.
3. Iodine is a non-metal but it is lustrous.
4. Carbon is a non-metal that can exist in different forms. And each form is called an allotrope.

• Diamond is an allotrope of carbon, which is the hardest natural substance known and has very high melting and boiling points.
• Graphite is another allotrope of carbon, which is conductor of electricity.

    5.  Alkali metals like lithium, sodium and potassium are so soft that they                  can be cut with a sharp knife. They have low densities and low                          melting points.

Most non-metals when dissolved in water give acidic oxides. On the other hand most metals give rise to basic oxides.