Write a short note on Metallic/Non-metallic properties of gr - 13 elements.
Answers
Answer:
Metals generally show less electronegative character. In compounds, they generally show a tendency to remain as positive ions. This property is often termed as electropositive character. Metals are electropositive elements.
Non metals are generally more electronegative due to their smaller atomic radii.
Let us examine the elements of 3 rd period.
3 rd period: Na Mg Al Si P S Cl
We know that Na and Mg are metals, Al and Si are semi metals (metalloids), P, S and Cl are non metals. So we find metals on left side and non metals on right side of the periodic table. This means metallic character decreases while non metallic character increases as we move along a period (from left to right).
Let us take group 14 (IVA) elements.
IVA group: C Si Ge Sn Pb
Here also we know that carbon is nonmetal. Si and Ge are metalloids.Sn and Pb are metals.
So we find nonmetals particularly at the right hand side top and metals at the left and right hand side bottom of the periodic table. This means metallic character increases while non metallic character decreases in a group as we move from top to bottom.
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.
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