Elements are classified broadly into two categories on the basis of properties:
Metals: Iron, Zinc, Copper, Aluminium etc.
Non – metals: Chlorine, Nitrogen, Hydrogen, Oxygen, Sulphur etc.
Apart from metals and non-metals, some elements show properties of both metals and non –metals,
e.g. Silicon, Arsenic, Germanium.They are called metalloids.

Comparison of physical properties of metals and non – metals:-


Property Metals Non-Metals
Physical State Metals are solid at room temperature. Except mercury and gallium. Non-metals generally exist as solids and gases, except Bromine.
Melting and boiling points Metals generally have high m.pt and b.pt except gallium and cesium. Non-metals have low m.pt and b.pt except diamond and graphite.
Density Generally high. Generally low.
Malleability and Ductility Malleable and ductile. Neither malleable nor ductile.
Electrical and thermal conductivity Good conductors of heat and electricity. Generally poor conductors of heat and electricity except graphite.
Luster Poses shining luster. Do not have luster except iodine.
Sonorous sound Give sonorous sound when struck. Does not give sonorous sound.
Hardness Generally hard except Na, K Solid non-metals are generally soft except diamond.

 

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