Assign the position of theelement havingouterelectronicconfiguration , (i) n s^(2) np^(4) for n = 3(ii)(n-1) d^(2)n s^(2) forn=4and (ii) (n-2) f^(7)(n-1)d^(1)n s^(2) for n= 6 in theperiodictable.

Assign the position of theelement havingouterelectronicconfiguration ,

1.	Assign the position of theelement havingouterelectronicconfiguration , (i) n s^(2) np^(4) for n = 3(ii)(n-1) d^(2)n s^(2) forn=4and (ii) (n-2) f^(7)(n-1)d^(1)n s^(2) for n= 6 in theperiodictable.
Answer» Solution :(i) n=3 suggeststhat theelementbelongs to thirdperiod . Sincethe lastelectronentersthe p- orbital thereforethe givenelement is p- blockelement .Furthersince thevalenceshellcontains6 (2+electrons thereforegroupnumberof theelement= 10 +no. of electrons in the valenceshell = 10 + 6 = Thecompleteelectronicconfigurationof the elementis `1 s^(2)2 s^(2)2 p^(6)3 s^(2)3p ^(4)` and theelement is( sulphur ) (II) n=4 suggetsthat theelementlies in the4thperiod. sincethe d- orbitals are incompletethereforeit isd-blockelement . the groupnumberof the element no. OFD- electrons + no. of s- electrons = 2 + 2 =4 . Thusthe elementslie ingroup 4 and4thperiod . Theconfigurationof the elementis `[Xe] 4 f^(7)5 d^(1) 6 s^(2). ` Theatomicnumber of theelement= 54 + 7 + 1 + 2= 64and thethe element is Gd(gadolinium ).