General Knowledge - Chemistry - Discussion

Fe (Z=26) configuration is [Ar]18 4S2,3d6.

Fe2+ means it will lose two electrons from its outer shell which is 4S.

So the configuration is [Ar]18 4s0, 3d6 . here the Fe2+ is stable because orbitals are fully filled or fully empty. d-electrons Numbers are 6.

Ne10 configuration is 1S2,2S2,2p6. p-electrons Numbers are 6
Mg12 configuration is 4s2,2s2,2p6,3s2 so s-electrons Numbers are 6
Cl17 configuration is 4s2,2s2,2p6,3s2,4p5. After applying half filled orbitals rule, the configuration will be 4s2,2s2,2p6,3s1,3p6 so p-electrons Numbers are 12
So, D is the correct answer.

The electron configuration of Fe+2 will be [Ar]4S13d5.

P electrons of Ne-2p6, s electron of Mg-3s2, d electron of Fe-3d6 but p electron of Cl is 3p5. So answer may be option D.

Thanks all for explaining the answer.

But I think the question is incorrect, as it asked.

It should be, The number of d-electrons in Fe2+ (Z = 26) is equal to that of.

To start up, the electron configuration of Fe atom is 1s2 2s2 2p6 3s2 3p6 4s2 3d6.

Since the problem is Fe2+ ion, than two electrons are removed from the atom so the correct configuration is 1s2 2s2 2p6 3s2 3p6 3d6.

Likewise, re-check your second configuration. I'm assuming you intended to write it as 1s2 2s2 2p6 3s2 3p6 4s2 3d4. This is incorrect because by then, the element would not be Fe2+ ion. Instead, this would be the electronic configuration of "chromium atom".

Basically, 2 electrons in the 4s orbital are removed because it is much farther away from the nucleus than 3d orbital. Since the electrons in 4s are farther and have weaker pull from the nucleus, there's more tendency for them to be dislodged from the atom.

The 4s orbital is at a higher energy level than the 3d orbitals and so because it is Fe(2+) the two electrons both leave the 4s orbital, leaving the 3d orbital with 6 electrons. And so:

No.of p electrons in Ne is 6(2p6).

No.of s electrons in Mg is 6(1s2,2s2,3s2).

No.of d electrons in Fe is 6 (d6).

No.of p electrons in Ci is 11(2p6,3p5).

I think option C is right.

Since outer most electron that is in the d orbital there number are 10 and also Fe2+ (Z=26) that's outer most electron numbers are 10 in d orbital.

1s2 2s2 2p6 3s2 3p6 4s2 3d6 is Fe electronic configuration.

While Cl is having 1s2 2s2 2p6 3s2 3p5, so Fe2+ is having configuration as below 1s2 2s2 2p6 3s2 3p6 4s0 3d6.

Actually half filled and full filled orbital are much more stable than partially filled orbital, that is why fe will first loose one electron from d orbital to half filled the 3d orbital then loose one other electron from 4s orbital and become more stable.