Question

How will you find the valence of chlorine , sulphur and magnesium???

Answer 1

based on vakency electrons we can say the vakency of elements
eg. cl-number of valence electrons in cl is 7
so for stability it can gain 1 electron instead of losing 7electrons
so valency of cl is 1
similarly the valency electrons in s is 6
it can gain 2 electrons for stability and hence vakency of s is 2 similarly for mg valency is +2 because it loses 2 electrons for stability

Answer 2

Atomic number of chlorine is 17 it's electronic configuration is 2, 8 ,7 it has to get 1 electron to attain noble has configuration that is argon. Atomic no. Of sulphur is 16 it's electronic configuration is 2,8,6 it has to get 2 electrons to attain the nearest noble gas configuration i.e, argon. Atomic no. Of magnesium is 12 it's electronic configuration is 2,8,2 it has to lose 2 electrons to get the nearest noble gas configuration that is neon. A element loses or gains electrons based on this.