Question

The electronic configuration of some elements are given below. a.1s2 b.1s2 2s2 2p6 In which group and period of the periodic table they are placed?​

Answer 1

In modern periodic table , properties of elements are periodic function of their atomic number.

position of any element :

number of outermost electrons = group number [ for s - subshell ]

bummer of outermost electrons + 10 = group number. [ for p - subshell ]

principal quantum number = period

(a) 1s², [ atomic no = 2 so, element is He]

principal quantum no = 1 and outermost electrons = 2

so, element belongs s-block, it positions ; 1st period and 2nd group .

(b) 1s², 2s² 2p^6 [ atomic no = 10, element is Ne ]

principal quantum no = 2 , outermost electrons = 8

so, element belongs to b-block and it positions ; 2nd period and (10 + 8) = 18th group