something simple but i need help

[dttom]

The electron configuration of V is [Ar] 3d3 4s2 and Cr is [Ar] 3d5 4s1, the electron in 4s subshell is transfered to 3d subshell for extra stability, stability by the half-filled 3d subshell. And Ir is [Xe] 4f14 5d7 6s2 while Pt is [Xe] 4f14 5d9 6s1. Mt first question is why Pt's configuration is like that but not [Xe] 4f14 5d8 6s2, how can the electron in 6s subshell be transfered to 5d subshell, in case of 5d subshell is either half-filled nor fully filled?

And one more question, where does the stability of Au and Pt come from?

[YT2095]

Xe, 6s2, 5d1, 4f14, 5d8

 

should be Pt (unless I just counted wrong?).

[dttom]

Xe' date=' 6s2, 5d1, 4f14, 5d8

 

should be Pt (unless I just counted wrong?).[/quote']

why there's two 5d(5d1 and 5d8)?

atomic number of Pt: 78

I think Pt is [Xe] 4f14 5d8 6s2 while wikipedia said that Pt is [Xe]4f14 5d9 6s1

[Tartaglia]

I can't give a definitive answer but the usual "half filled subshell" explanation is a simplification. The promotion of an electron usually arises when the spin exchange energy gained excedes the energy required to promote. This is most usual when filling or half filling a subshell but doesn't necessarily have to be the final electron making up a half or full shell

[YT2095]

because I`m working directly from a periodic table, and 5d1 (La), then we jump to the `f` block through all 14 and back to 5d2 (Hf).

and all this, From Xenon is preceeded by 6s2, and so I don`t see how that can come Last either!?

[woelen]

YT, you can take 5d electrons together. The order in the comma separated list does not tell anything about the order in which electrons are added to the atoms, when traversing through the periodic table.

 

Indeed, explaining why certain orbitals are filled first and why there are some irregularities, such as V/Cr and Ir/Pt, cannot be explained by means of simple rules. When precise quantummechanical computations are performed, then you'll see that the observed electronic configurations are energetically the lowest (and the most stable). So, for precise detailed explanations, one has to resort to complicated and detailed computations, there are no simple rules anymore, which can explain all these things.

[YT2095]

well if you`re going on the Electrons themselves then 6s1 is the correct ending for Pt.

 

Shells for Pt, would be k2 l8 m18 n4s2 n4p6 n4d10 n4f14 o5s2 o5p6 o5d9 p6s1

of course this is only accurate for the Ground State.

[dttom]

well, what about the outstanding stability of the element Pt?

[Tartaglia]

Platinum's stability is probably due to the lanthanide contraction. This makes it much smaller than you would expect and so the outer electrons are much more tightly bound