Metals and Non-Metals

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Elements can be classified as metals, non-metals and metalloids on the basis of their physical and chemical properties. 

Physical properties of metals:

Lustre: Metals in their pure state have a shining surface called metallic lustre.

Malleability: Metals are malleable i.e can be beaten into thin sheets.

Note: Gold and silver are the most malleable metals.

Ductility: The ability of metals to be drawn into thin wires is called ductility. 

• Gold is the most ductile metal. 

Note: 1 gramof gold can be drawn into a thin wire about 2km long because of their malleability and ductility.

Conductivity: Metals are good conductors of heat and electricity

• Silver and copper are good (best) conductors of heat and electricity. 

• Lead and mercury are comparatively poor conductors of heat and electricity. 

Sonorous: Metals are sonorous i.e they produce a sound when hit (strike) with a hard surface (object).

• The metals that produce a sound on striking a hard surface are said to be sonorous. 

Melting and Boiling point: All metals generally have high melting and boiling points except gallium and caesium whic have very low melting points and will melt if kept on the palm.

Physical State: All metals are generally solid at room temperature except mercury which exist in liquid state at room temperature.

Hardness: All metals are generally hard and cannot be easily cut with a sharp knife except (lithium, sodium, potassium) are so soft that they can be easily cut with a knife. 

• Chromium is the hardest and caesium is the softest metal.

Density: Generally all metals have high density except (lithium, sodium, potassium) which have low densities.

Some examples of metals – iron, copper, aluminium, magnesium, sodium, lead, zinc etc.

Physical properties of Non metals:

• Non-Metals have properties opposite to that of metals.

Lustre: Non-metals do not have Lustre i.e they are non lustrous except Iodine and diamond which is a non-metal but lustrous.

Malleability and Ductility: They are neither malleable nor ductile.

Conductivity: They are bad conductors of heat and electricity, except for graphite, which conducts electricity.

Sonorosity: They are non-sonorous i.e do not produce sound when hit with a hard object.

Melting and Boiling point: They have low melting and boiling point except diamond and graphite which have very high melting and boiling point.

Physical states: Out of 22 non-metals 10 are solids, 11 are gases and 1 is liquid which is bromine.

Hardness: Non-metals are generally soft except diamond and boron.

Note: Diamond is the hardest natural substance known.

• They are actually brittle i.e breaks easily when hammered.

• Some of the examples of non-metals - carbon, sulphur, iodine, oxygen, hydrogen, etc.

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