[vhpk]

Why does those elements stay in the same group but their electron configurations are different: Ni,Pd,Pt.
Maybe it is related to endurance of the atom, I don't know

[moussa]

what do you specificly mean by different electronic configuration??? if they have exactly the same one they would be the same element.

• they all belong to the same group (d8)
  they show similar chemical properties
  capable of forming CN4 compounds
   their radii are not that different in size

[enahs]

what do you specificly mean by different electronic configuration??? if they have exactly the same one they would be the same element.

Not at all. It is the number of protons that make an element and element.

Na⁺ as the exact same electronic configuration as Ne. O^- has the exact same electronic configuration as F.

Ni, Pd and Pt are in the same group because that is how we define the periodic table. We group them as such that they have the same valence electron configurations, just as you descend the group the principal quantum number increases by 1.

Chemistry is the study of valence electrons, as a result, having the same valence electron configuration, they share chemical properties.


In your particular case you have, you are seeing what is some of the typical anomalies for the transition metals.

Nickel fills up the electrons just as you would expect.

Palladium, is different. the 4d and the 5s orbitals are roughly at the same energy level. If you apply the Aufbau principle and Hunds rule, keeping into account the fact that the 4d and 5s are of basically the same energy level. It is therefor more energetically stable to place the two electrons from the S orbital into the D orbital. This gives a completely full d orbital. Completely full or exactly half-full orbitals are significantly more energetically stable (completely full being more stable then half). Any other way you arrange them will result in more instability).

Platinum begins the usage of the f orbitals, and that makes things all messy. You must remember that what you see as the periodic table is a shortened version, and the lanthanide's are on that row between the transition metals and S-block.
Extended Periodic table

There is more to the story then just those few things. Size, electron shielding, effective nuclear charge, etc etc come into play.

It does not really effect the chemical properties of the elements, at least not in anyway you are ready to start learning.



More reading:
http://www.fordhamprep.org/gcurran/sho/sho/lessons/lesson36.htm
http://library.thinkquest.org/10429/high/eleconfig/electron.htm
http://en.wikipedia.org/wiki/Electron_configuration
http://en.wikipedia.org/wiki/Valence_shell