help! an actual DAT question from 80s

[yahoogoogle]

Advertisement - Members don't see this ad

Iron, Fe has the atomic number 26. Its ion Fe3+ has the following ground state configuration

the answer is

3d
[Ar](1)(1)(1)(1)(1)
4s
()

rather than


3d
[Ar](1)(1)(1)()()
4s
(11)

4s is lower in energy than 3d. is this a mistake or something

 

[joonkimdds]

Iron, Fe has the atomic number 26. Its ion Fe3+ has the following ground state configuration

the answer is

3d
[Ar](1)(1)(1)(1)(1)
4s
()

rather than


3d
[Ar](1)(1)(1)()()
4s
(11)

4s is lower in energy than 3d. is this a mistake or something

i think u r right, but i m not an expert. someone answer this for him 😀

 

[AaBbZz]

The answer should be the first one listed. The transition metal Iron has a half filled d subshell. The half filled d subshell is stable and wants to keep it that way so it actually losses its two s subshell electrons first. This is a property of all half filled transition metals. So the first answer is in fact correct. Don't let the energey level number trick you.

 

[PD3]

The answer should be the first one listed. The transition metal Iron has a half filled d subshell. The half filled d subshell is stable and wants to keep it that way so it actually losses its two s subshell electrons first. This is a property of all half filled transition metals. So the first answer is in fact correct. Don't let the energey level number trick you.

I don't believe this has to do with half filled subshells. A 4s is higher in energy than a 3d, therefore the ion will lose both 4s electrons first, then one 3d electrong leaving a configuration of [Ar] 3d5.

If I am wrong someone correct me.

 

[joonkimdds]

I don't believe this has to do with half filled subshells. A 4s is higher in energy than a 3d, therefore the ion will lose both 4s electrons first, then one 3d electrong leaving a configuration of [Ar] 3d5.

If I am wrong someone correct me.

really? but we need to fill out 4s first before we fill the 3d orbital.
so shouldn't we start by removing electrons from 3d orbital first and then remove 4s later?

 

[PD3]

Actually the 3d fills before the 4s.

 

[joonkimdds]

Actually the 3d fills before the 4s.

really?

but when we write the electron configuration, don't we usually write 4s before 3d? i thought that means 4s fills out first.

 

[PD3]

Let me check again. I think it's correct, but I can't find an image to show it. Anyone that can help?

 

[AaBbZz]

Then what would be the answer to a 2+ion of 4s 3d7 because I think it would be 4s 3d5? I could be wrong though if anyone could clear this up that would be wonderful

 

[PD3]

Here is an image showing how it is laid out properly. http://dkreutz.basd.k12.wi.us/OrbitalEnergies.jpg

I believe this is why most all of the transition elements have a lower oxidation state of +2. This makes sense:

Fe [Ar] 4s2 3d6
Fe+2 [Ar] 3d6
Fe+3 [Ar] 3d5 - Notice a half fille subshell now.

Ag [Kr] 5s14d10
Ag+ [Kr] 4d10 - Notice it kept the full shell

 

[joonkimdds]

Here is an image showing how it is laid out properly. http://dkreutz.basd.k12.wi.us/OrbitalEnergies.jpg

I believe this is why most all of the transition elements have a lower oxidation state of +2. This makes sense:

Fe [Ar] 4s2 3d6
Fe+2 [Ar] 3d6
Fe+3 [Ar] 3d5 - Notice a half fille subshell now.

Ag [Kr] 5s14d10
Ag+ [Kr] 4d10 - Notice it kept the full shell

http://upload.wikimedia.org/wikiped..._orbitals.svg/800px-Electron_orbitals.svg.png
Here is a picture showing that 4s comes before 3d.
This is how I learned in Gchem and I think the topic creator agrees with me
and that's why the topic creator got confused and wrote this thread.

 

[AaBbZz]

So it does have something to do with half and full shell d orbitals right? so for something that is 4s2 3d7 +2 ion would it be 4s2 3d5? or would that element (not looking at the periodic table to see what the actual name is) not even become a 2+ion?

 

[PD3]

I am certainly not immortal to error. This is the way I thought it was, but could certainly be incorrect. I will wait for others to post their opinion.

 

[joonkimdds]

I am certainly not immortal to error. This is the way I thought it was, but could certainly be incorrect. I will wait for others to post their opinion.

but u r smart

 

[PD3]

Anyone else have thoughts on this?