Question

how to know electronic configuration ​

Answer 1

there is your answer

Answer 2

to  calculate an electron configuration, divide the periodic table into sections to represent the atomic orbitals, the regions where electrons are contained. Groups one and two are the s-block, three through 12 represent the d-block, 13 to 18 are the p-block and the two rows at the bottom are the f-block. The row numbers one through seven represent the energy levels that contain the orbitals and electrons.