Explain the classification of elements based on chemical behavior and on physical properties.

Explanation

Based of chemical behavior:
(i) Main group elements: All s-block and p-block elements excluding 18 group elements are called representative elements.
(ii) Noble gases: The 18th group elements are exclusively called noble gases. They have completely filled electronic configuration as nsa np. These elements are highly stable.
(iii) Transition elements: The elements of d-block are called transition elements. These include elements of groups from 3 to 12th lying between s-block and p-block elements.
(iv) Inner transition elements: The elements of f-block are called inner-transition elements. These consist of lanthanides and actinides, with 14 elements in each.
Based of physical properties:
(i) Metals: Metals comprise more than 78% of all known elements. They are usually solids at room temperature (except Hg, Ga and Cs). They have high melting and boiling points. They are good conductors of heat and electricity.
(ii) Non-metals: Non-metals are usually solids or liquids or gases at room temperature with low melting and low boiling points (except boron and carbon). They are poor conductors of heat and electricity. Most of the non-metallic solids are brittle and are neither malleable nor ductile.
(iii) Metalloids or Semi-metals: Some elements in the periodic tables show properties that are characteristic of both metals and non-metals. They are called metalloids. Example: Silicon, germanium, arsenic, antimony and tellurium.