![]() ![]() ![]() I do not understand the "completely filled" state. The "half filled" 3d orbital of Cr is more stable because the 4s energy level is close to the 3d energy levels - therefore moving electrons from the 4s energy level into the 3d minimizes the repulsion between the electrons, and entropy is favored (if the two electrons stay in the 4s there is more order). Simply stating because "half-filled" and "completely filled" is more stable is not even an answer.Ītoms can't desire or want to be "filled" - that is anthropomorphistic (as stated by Ferdinand in the post above). Is someone going to answer the question that was asked? Such a simple system exhibits amazingly complex behavior, which only can be understood by simply running the simulation for a long time. ![]() Simple underlying physical laws can give rise to really complex behavior, which only can be understood by performing massive computations.Īnother nice example of a very simple system, following very simple laws is a three-body mechanical system with Newtonian laws of gravity. Probably this is not a nice answer in terms of easy understanding, but sometimes you have to take things as they are. Only then you see the very subtle differences in energy levels. This is a hell of a job and requires a lot of computational power, but it has been done for us already. There only is one way to really understand all these oddities and that is numerically solving the quantum mechanical wave equations for all electrons in an atom, also taking into account relativistic effects. Cd), or look at Pt and Au, over there this reasoning does not work anymore. But now look at the second row of transition metals (elements Y. So, I agree with the answers, because they make it easy to remember which are the oddities for the transition metals. In the lanthanides there is even more complicated behavior with oddities in between (the f orbitals come in play then). It might be that all this reasoning about shells want to be half full and so on is correct, but there are counter examples. Keeping in mind what has been said in this thread, you should even be able to figure out the 'odd' ones. This is nice and stable and everybody's happening.įor fun, pick any random d or f block element and write out it's electron configuration before you look it up. As a result, you get a completely filled 3d shell and a half-filled 4s shell. So in copper, an electron is taken from the 4s shell and added to the 3d shell along with the extra electron that copper has over nickel. Anything in between isn't good and if it's possible to rearrange the electrons to accomodate that then you'll probably see it happen. Shells want to be either half full, or totally full. Since the 3d shell can hold a total of ten electrons, it would wind up being 9/10'th full which is an odd fraction. If you just add one electron to that as you move to copper, then you'd have four totally filled shells and one half-filled shell. In Nickel (4s2-3d8) you have four totally filled 3d subshells and one empty one. When you move from Nickel to Copper, you would logically think that you'd go from 4s2-3d8 to 4s2-3d9. Remember that the 4s shell fills in before the 3d shell does, because as Yggdrasil pointed out, their energy levels are pretty much the same.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |