Question

An element x has mass number 35 and number of electron 18 write atomic number and electronic configuration of 8 also write group and period number and valency of x

Answer 1

• Atomic no=18 (as it is a neutral element so no. of electron=no. of proton)
• electronic configuration of 8=

1s2 2s2 2p4

• electronic configuration of x=1s2 2s2 2p6 3s2 3p6
• period of x=3(maximum principle quantum number=3), group=18, valency=0(p subshell is completely filled)