Question

The ion [Co(NH3)6]2+

isoctahedral and high spin. This complex is:
A. paramagnetic, with 1 unpaired electron.
B. paramagnetic, with 3 unpaired electrons.
C. paramagnetic, with 4 unpaired electrons.
D. paramagnetic, with 5 unpaired electrons.
E. diamagnetic.

Answer 1

Step-by-step explanation:

The answer would be B.

As paramagnetic with 3 unpaired electrons. Since there are 6 ligands around the Co+2 ion it isoctahedral and these ligands are neutral. This makes the overall charge on the complex +2 and therefore comes from the configuration for Co+2 which is [Ar] 3d7. Since it is in high spin you must fill all the orbitals with at least one electron and then pair up any that remain. If you do this, 3 unpaired electrons remain. Para magnetism occurs in substances with unpaired electrons.