If you can't explain something properly, it is much better just to accept it than to make up faulty explanations which sound OK on the surface but don't stand up to scrutiny! You can't assume that looking nice and tidy is a good enough reason! Neither can you use the statement that a full d level (for example, in the copper case) is stable, unless you can come up with a proper explanation of why that is. But in this case, it isn't true that the half-filled state is the most stable - it doesn't seem very reasonable, but it's a fact! The real explanation is going to be much more difficult than it seems at first sight. Again the electron repulsions must be minimised - otherwise it wouldn't take up this configuration. Tungsten has the same number of outer electrons as chromium, but its outer structure is different - 5d 46s 2. The obvious explanation is that chromium takes up this structure because separating the electrons minimises the repulsions between them - otherwise it would take up some quite different structure.īut you only have to look at the electronic configuration of tungsten (W) to see that this apparently simple explanation doesn't always work. People sometimes say that a half-filled d level as in chromium (with one electron in each orbital) is stable, and so it is - sometimes! But you then have to look at why it is stable. Any simple explanation which is given is faulty! There is no simple explanation for it which is usable at this level. Note: This is something that you are just going to have to accept. You will notice that the pattern of filling isn't entirely tidy! It is broken at both chromium and copper. The electronic structures of the d block elements shown are: Sc The first row of these is shown in the shortened form of the Periodic Table below. The elements in the Periodic Table which correspond to the d levels filling are called d block elements. If you do follow the link, use the BACK button on your browser (or the History file or Go menu) to return quickly to this page. It takes you to a page explaining atomic orbitals and then on to other pages about electronic structures. Note: If you aren't sure about atomic orbitals and electronic structures, you really need to follow this link before you go on. You will remember that when you are building the Periodic Table and working out where to put the electrons using the Aufbau Principle, something odd happens after argon.Īt argon, the 3s and 3p levels are full, but rather than fill up the 3d levels next, the 4s level fills instead to give potassium and then calcium. They don't - there's a subtle difference between the two terms. The terms transition metal (or element) and d block element are sometimes used as if they mean the same thing. The electronic structures of transition metals You will find some of this covered quite briefly on this page with links to other parts of the site where the topics are covered in more detail. These include variable oxidation state (oxidation number), complex ion formation, coloured ions, and catalytic activity. This page explains what a transition metal is in terms of its electronic structure, and then goes on to look at the general features of transition metal chemistry. THE GENERAL FEATURES OF TRANSITION METAL CHEMISTRY
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