Summarize the rules for writing of distribution of electrons in various shells for the first eighteen elements.
Following rules are followed to fill electrons in different energy levels,
(i) If n gives the number of orbit or energy level, then 2n2 gives the maximum number of electrons possible in a given orbit or energy level. Thus
First orbit or K-shell will have 2n2 =2 x 1 = 2 electrons
Second orbit or L-shell will have 2n2 = 2 x 22 =8 electrons
Third orbit or M-shell will have 2n2 = 2 x 23 =18 electrons
(ii) If it is the outermost orbit, then it should have not more than 8 electrons.
(iii) There should be stepwise filling of electrons in different orbits, i.e., electrons are not accommodated in a given orbit if the earlier orbits or shells are incompletely filled.
