Hi all. These are some questions that I've gathered from quite a bit of study that I'm still baffled by... and feel I should understand before going any further. Don't feel that you have to answer all of them. Anything is of help.
1. Regarding the benzene ring, my chemistry book, it says "we can imagine the 6 valence electrons, one from each carbon atom, belonging to the whole molecule, instead of being localised in the three double bonds". I'm not sure where it's getting the '6' from. I mean I know that carbon has 6 electrons, but I don't think that's got anything to do with it. Given that carbon is tetravalent, I would have thought of it as there being 4 valence electrons for each carbon atom... so that would be 4 by 6, which would be 20 valence electrons in the entire structure.
2. This question is to do with sub orbital. I know there's a total number of 18 electrons accounted for within the orbitals of the third energy level; 3s2, 3p6, 3d10; and I've shaded these elements a certain colour on my periodic table. What I'm asking about here is about the orbital of the fourth energy levels. I want to shade these in my periodic table. I think 4d orbital is the elements from 39 to 48 in the d block, but I want to know which ones are in the 4f energy level?
3. In the case of the water molecule, can one of these lone pairs be thought of as the electrons within 2s2, with the other lone pair being thought of as the electrons within 2px2? Likewise I'm wondering about the ammonium molecule, and whether I can think of the one lone pair on the N atom as being the electrons in the 2s2 orbital? If I were to ask about O2, would it be that (on either of the oxygen atoms) that one of the lone pairs is from 2px2, and the other lone pair is from 2s2?
4. Following on from the reasons why elements Cr & CU have different electronic configurations than what one might expect due to the fact that p, d and f sublevels are more stable if they are either half or completely filled. So my question is, if this is the case, then how come the same isn't true for carbon and fluorine?
5. What's the deal with Boron Trichloride only achieving an outer electronic configuration of 6? If it were ionic bonds I could understand, but it's covalent bonds! From what I can see, it would need another chlorine atom to join in in order for there to be another shared pair of electrons, thereby giving the octet. Of course that would make it tetravalent; which it's not! In thinking of it in terms of sigma and pi bonds, I can see how the half filled x orbital would form a sigma bond, but this way of thinking about it doesn't help me out either! The same issue with Beryllium chloride.