Question

Which one is not paramagnetic among the following? [at. no. of $Be = 4, N e = 10$ , $A s= 33,Cl= 17$]

• A. $Cl^-$
• B. Be
• C. $Ne^{2+}$
• D. $As^+$

Answer 1

The Correct Option is A

To identify which of the given options is not paramagnetic, we need to determine the electronic configuration of each species and check for unpaired electrons. A substance is paramagnetic if it has one or more unpaired electrons; otherwise, it is diamagnetic.

1. Cl^-\ (Chloride\ ion):
   • The electronic configuration of chlorine (Cl) is [Ne]\ 3s^2\ 3p^5.
   • The chloride ion (Cl^-) has one additional electron, giving it the configuration [Ne]\ 3s^2\ 3p^6.
   • This configuration is fully filled with no unpaired electrons, thus it is diamagnetic.
2. Be (Beryllium):
   • The electronic configuration of Be is 1s^2\ 2s^2.
   • It has all paired electrons. Thus, Be is diamagnetic.
3. Ne^{2+}\ (Dineon\ ion):
   • The electronic configuration of Ne is 1s^2\ 2s^2\ 2p^6.
   • Removing two electrons gives 1s^2\ 2s^2\ 2p^4.
   • This configuration has two unpaired electrons in the 2p orbitals, making it paramagnetic.
4. As^+\ (Arsenic\ ion):
   • The electronic configuration of As is [Ar]\ 3d^{10}\ 4s^2\ 4p^3.
   • Removing one electron gives [Ar]\ 3d^{10}\ 4s^2\ 4p^2.
   • There are two unpaired electrons in the 4p orbitals, making it paramagnetic.

Therefore, among the given options, Cl^-\ is the species that is not paramagnetic as it has no unpaired electrons. It is diamagnetic.