what is electronic configuration of an element with atomic number - 27 and 28?

Dear Student,

Number of electrons in a particular shell is given by the formula 2n² where n denotes the shell number i.e., n=1(K),2(L),3(M),……

Shell K (n=1) contains maximum of 2 electrons (2 x 1²=2).

Shell L (n=2) contains maximum of 8 electrons (2 x 2²=8).

Shell M (n=3) contains maximum of 18 electrons (2 x 3²=18).

                                                                                         K  L   M    N

Electronic configuration of element with atomic number 27:  2   8   15   2

Electronic configuration of element with atomic number 28:  2   8   16   2

Shells or energy levels (i.e., L,M,N etc.)are divided into sub-levels or sub-shells having different energies due to which the filling of electrons in N shell also takes place before M shell is completely filled (in the electronic configurations shown above). The reason for these kind of configurations will be explained in higher classes.