How does the electronic configuration of an atom related to its position in the modern periodic table ?

Explanation

In the periodic table elements are placed acrording to their atomic number. If an element has only one shell in its electronic configuration it is placed in the first period, if the element has two shells then it is placed in the sccond period and so on. Vertical column in the periodic tuble in group all the elements have same number or valence clectron.
No. C1 35 and CI - 37 will be placed in same sior. The moderan periodie table is based on atomic numbers not atomic mass since, both CI-35 and Cl - 37 have same atomic numbers hence they are placed in same slot.