Question

An element has atomic number 17.Where would you expect this element in the long form of periodic table?Why?

Answer 1

If an element has 17 as its atomic number, this element can be expected in 17th group of periodic table which is of halogens and it'll be in the 3rd period.

This placement depends upon the electronic configuration.

As, it would be 2, 8, 7 in this case.

7 in the outermost shell states that its group is 7 and by the " spdf " shell arrrangement its period would be 3rd.

This element is Chlorine ( Cl ).