Metals : The metals are characterised by their nature of readily giving up the electrons.
1) Metals comprise of more than 75% of all known elements and most of them appear on the left hand side of the periodic table.
2) Metals are usually solid at room temperature (except mercury).
3) They have high melting and boiling points and are good conductors of heat and electricity.
Non – Metals :
1) Non-metals do not lose electrons but take up electrons to form corresponding anions.
2)Non-metals are located at the top right hand side of the periodic table.
3)Non- metals are usually solids or gases (except bromine whish is liquid) at room temperature with low melting and boiling points.
4) They are poor conductors of heat and electricity.
Metalloids (Semimetals ) :
1) Some elements lying at the border of metallic and non- metallic behaviour possess the properties that are characteristics of both metals and non – metals. These elements are called semimetals or metalloids.
2) The metalloids comprise of the elements B, Si, Ge, As, Sb, Te and Po.
3) Variation of metallic character across a period : Metallic character decreases along a period due to increase in ionisation energy.
>>Non – metallic character increases with increase in atomic number across a period.<<
4) Variation of metallic character along a group : Metallic character increases on going down a group from top to bottom. This can be explained in terms of decrease in lionisation energy on going down a group from top to bottom.
>>Metallic character decreases and non-metallic character increases across a period from left to right, while metallic character increases and non-metallic character decrease down the group.<<
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