In group- The electropositive or metallic characters increases from top to bottom in a group.
ELECTRO-NEGATIVE OR NON- METALLIC CHARACTERS: the tendency of an element to accept electrons to form an anion is called its non metallic or electronegative character. The elements having high electro-negativity have higher tendency to gain electrons and forms anion. So, the elements in the upper right hand portion of the periodic table are electro-negative or non-metallic in nature.
Periodicity:
( i) In period- The electro-negative or non- metallic characters increases from left to right in a period.
( ii) In group- The electro-negative or non-metallic characters decreases from top to bottom in a group.
REACTIVITY OF METALS: Periodicity:
( i) In period- The tendency of an element to lose electrons decreases in a period. So the reactivity of metals decreases from left to right in a period.
( ii) In group- The tendency of an element to lose electrons increases in a period. So the reactivity of metals increases from top to bottom in a group.
REACTIVITY OF NON- METALS:
( i) In period- The tendency of an element to gain electrons increases in a period. So the reactivity of non-metals increases from left to right in a period.
( ii) In group- The tendency of an element to gain electrons decreases in a group. So the reactivity of non-metals increases from top to bottom in a group.