Question

what is valency describe it briefly and also write about valence shells

Answer 1

Valency is tendency of any atom to give or take any electron to obtain noble gas configuration.
Valence shell is the last shell of any atom

Answer 2

valency of an atom is the number of electrons that an atom can lose or gain during a chemical reaction.the last shell of an atom is known as the valence shell and the electrons in it is known as the valence electrons.metals generally have 1,2 or3 electrons in their valence shell and non-metals have 5,6,7....metals lose electrons to form cation and non-metals lose electrons to form anion...
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