Chemistry

Metallic and Non-metallic Character :
Group 1 to 12 are metals. Group 13 to 18 comprise non-metals, metalloids and metals.
Metalloids : Those elements which resemble both metals and non-metals are called metalloids. They are also called semi-metals, e.g., Boron, Silicon, Germinaium, Arsenic, Antimony, Tellurium and Polonium.
Properties of Metals :
(i) The are malleable.
(ii) They are ductile.
(iii) They are good conductors of heat and electricity.
(iv) They have generally 1 to 3 valence electrons.
(v) They have the same or less number of electrons in their outermost shell than the number of shells.
(vi) They are mostly solids.
Properties of Non-metals :
(i) They exist in solid, liquid or gaseous state.
(ii) Non-metals are generally brittle.
(iii) They are non conductors.
(iv) They have 4 to 8 valence electrons.
Variation of Metallic Character :
Metallic character increases down a group due to decrease in ionisation energy. It decrease along a period due to increase in ionisation energy from left to right
Variation of Non-metallic Character :
Non-metallic character decreases down a group because of decrease in electron affinity which is due to increase in atomic size. Along a period, non-metallic character increases from left to right due to increase in electron affinity which is due to decrease in atomic size.