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:-
|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.|