Question

Which decides the place of an element in periodicsl table?

Answer 1

it si decided  by  the elements  atomic number

Answer 2

Mostly, No. of valence electrons and no. of shells in an atom decides the place of an atom in the periodic table according to the K,L,M,N... type of configuration. The SPDF method of assigning the place also includes having a look at the no. of subshells along with normal shells. Hope it helps