Question

Can we find valency of all elements in periodic table by electronic configuration method?

Answer 1

yes ,we can find the valency

Answer 2

yes we can find valency of elements by electronic configuration method but only up to first 30 elements after that we can apply aufbau's principle to find valency
(if u want me to explain aufbau principle plz comment )
aufbau principle states that the shells of atom comprises of subshells. .s,p,d,f
we can fill electrons in them by the following rule .. 1s 2s 2p 3s 3p 4s........ s shell contains 2 electrons p contains 6 d 10 and f 14
we can fill electrons in each subshell and electrons in last subshell is valency