Question

State the rules behind writing electronic configuration atom

Answer 1

hey..

electeonic configuration is the distribution electrons in the shell...so we need to follow Aufbau's principle in writing the EC of an atom..Aufbau's principle states that the electron enter the higher shell only after filling the lower energy shell..so first 1s should be max. filled and then 2s and 2p..3s..3p so on..

Answer 2

hay mate
we fill the orbits or shell of atom to use 2n^2 formula