Chemistry
Explain the meaning of the term 'valency'. State why the valency of the metal potassium is +1 and of the non-metal chlorine is -1.
Answer
Valency is the number of hydrogen atoms which can combine with or displace one atom of the element or radical so as to form a compound.
Valency of a metal is the number of electrons lost per atom of the metal. Valency of all metals and hydrogen is considered positive. Therefore, valency of potassium is 1+ as it has 1 electron in outer most shell which it loses and becomes K+.
Valency of non-metal is the number of electrons gained per atom of the non-metal. Valency of all non-metals/groups of non-metals is taken as negative. Therefore, valency of non-metal chlorine is -1, because chlorine [Cl] has 7 electrons in valence shell and gains 1 electron and becomes [Cl–].
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