Science and Technology for UPSC Examinations [Chemistry] Part 11- Metals versus Non-Metals
Metals versus Non-Metals
There are 118 elements identified element so far, the latest being ununseptium in 2010. Of the 118 known elements, only the first 98 are known to occur naturally on Earth; 80 of them are stable, while the others are radioactive, decaying into lighter elements over various timescales from fractions of a second to billions of years.
On the basis of their properties, the elements are broadly classified into metals and non-metals. The metals have been placed on the left hand side and in the centre of the periodic table, whereas non-metals have been placed on the right hand side. The element hydrogen is though, placed on the left hand side of the periodic table. There are certain elements which show the properties of both metals and non-metals and these are called metalloids. The metals and non-metals in the periodic table are separated by a zig-zag line of metalloids. The metalloids are bismuth, silicon, germanium, arsenic, antimony, tellurium and polonium.
The following table differentiates between metals and non metals with their general properties.
|Except mercury, all metals all solids at room temperature||Non-metals can be solids, liquids or gases. For example bromine is a liquid.|
|Metals are hard and malleable and can be beaten into thin sheets.||Non-metals are brittle|
|They are generally lustrous||They are generally not lustrous (Iodine, graphite and diamond are lustrous)|
|They are ductile and can be stretched into wires.||They are generally non ductile except some as Carbon fibre|
|They are sonorous and clang if they are hit.||Non-sonorous|
|They are good conductors of heat and electricity.||Except some examples such as Graphite, Non-metals are bad conductors of heat and electricity|
|Generally hard (except sodium and potassium) and have high tensile strength||Generally soft exception diamond.|
|Generally high density||Generally low density|
|Generally high melting and boiling points (except sodium and potassium)||Generally low melting and boiling points (exception graphite)|
|Metals react with oxygen and forms metal oxides. which are mostly basic in nature. Aluminium and zinc oxides exhibit acidic as well as basic properties. Such metal oxides are known as amphoteric oxides.||Non-metals react with oxygen and form acidic or neutral oxides. Carbon and sulphur form acidic oxides. Hydrogen forms a neutral oxide|