Question

Why sodium and chlorine has valency of 1, yet they show different chemical properties. why?
(class 10 CBSE SAMPLE PAPER 2017-18 SCIENCE)

Answer 1

Sodium(Na) has valence shell electronic configuration of 2, 8, 1 and tends to lose one electron to achieve stable electronic configuration on the other hand chlorine (Cl) has a valency electronic configuration of 2,8,7 and tends to gain one electron to achieve stable electronic configuration. So they have different valence shell electronic configuration and thus different chemical properties. However their valency  is same that is 1.

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