Why are metals electropositive and non-metals electronegative in nature? Illustrate by giving an example of each. Why does metallic character of elements increase down a group?

Explanation

a] Metals have 1-3 valence electrons and hence they tend to lose electrons to attain noble gas configuration. For example, Sodium is a metal which has | valence electron. It can easily lose this valence electron rather than gain 7 more electrons to attain a noble gas configuration while forming compounds. Hence, metals are electropositive in nature. Non-metals have 5-8 valence electrons (except Carbon which has 4 valence electrons). It is easier for them to gain electrons to acquire noble gas configuration and hence they are electronegative. Example: Nitrogen is a non-metal with 5 valence electrons which gains 3 electrons during bonding. Hence, it is electronegative.
b] Down a group, the number of electron shells increases and hence the distance between valence electrons and nucleus increases. The attractive force between them goes on reducing thereby making it easier to lose electrons. This increases electropositivity and hence the metallic character.