InterviewSolution
Saved Bookmarks
InterviewSolution
| 1. |
Gaseous metal ion `M^(2+)` has `5` unpaired electron. What is the atomic number?A. `26`B. `25`C. `27`D. `24` |
|
Answer» Correct Answer - B Let us write the electronic configuraiton of `Z = 24`: `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(5)4s^(1)` or simply `[Ar] 3d^(5)4s^(1)` `(Z = 25):[Ar] 3d^(5)4s^(2)` `(Z = 26):[Ar]3d^(6)4s^(2)` `(Z = 27):[Ar]3d^(7)4s^(2)` If we take `2e^(-)s` from each of the above configurations, we notice that only `(Z =25)` leads to the formation of `M^(2+)` with `5` unpaired electrons. Shortcut method: The presence of `5` unpaired electrons can be justified by`d^(5)` subshell only. Thus, the electronic configuration of `M^(2+)`ion will be `1s^(2)2s^(2)2p^(6)3s^(2)3p^(6)3d^(5)` accounting for `23e^(-)s`. Thus, neutral `M` atom should have `23 +2 = 25e^(-)s`, i.e., the atomic number should ber `25`. |
|