![]() ![]() ![]() Those electrons are not of equivalent energy, and Opportunity for carbon to form four bonds, however, Up to the two P orbital, so we're in the excited state now. Show that, so we've moved one of those electrons It up to the P orbital here, so let me go ahead and One of these electrons in the two S, and promote That he said was, you could go ahead and take out The electron configuration here, and so to explain this difference, Linus Pauling came up with Here, and everything's of different energies, and so, what we see from the dot structure and experimentally, doesn't quite match up with This implies that carbon would only form two bonds,īecause I have these unpaired electrons right The valence electrons in the outer shell. Here, that would be these four electrons here, If we look at those four valence electrons on our orbital notation In the two S orbital, and then two P two, and so, I'm assuming you already know yourĮlectron configuration, so it would look something like that. It's one S two, so go aheadĪnd put in two electrons in the one S orbital, two S two, go ahead and put in two electrons We look at the electron configuration for carbon, let's go ahead and do that right now. The table over here, let me go ahead and highlight those four valence electrons, those should be equivalent, and if And so the four valence electrons that carbon brought to Like this, with carbon with its four bonds to hydrogen around it, like that, and in methane,Īll of these bonds are equivalent, in terms of things like bond length and energy. One valence electron, and that gives us the Lewis Dot structure. So we go ahead and draw in our hydrogens with Start with carbon, and its four valence electrons,Īnd then we would put hydrogen around that each hydrogen has one valence electron, Want to draw a dot structure for methane, I would This is valence bond theory.We're going to look at the SP three hybridization present in methane and ethane Somewhere in between these extremes is a useful simplification that allows organic chemists to predict the shape, reactivity and many of the properties of an organic molecule. The most accurate way to represent a molecule is using molecular orbital theory. The easiest way to represent a molecule is with a drawing of the skeletal structure. We only mention them as they are very useful when looking at reactions and those of you that take chemistry further than first year will need them. Antibonding orbitals are the result of magic (maths) and are confusing. One is going to be the σ bond (or π bond) we are interested in but what is the other? It is something called an antibonding orbital. If you start with two orbitals and combine them there must still be two orbitals. This meant that as we started with four glasses we end with four glasses or if we start with four orbitals we have to end with four orbitals. In that we told you that when you mix four glasses of liquid the volume of liquid stays the same. What does this mean? Think back to the gin and tonic analogy of hybridisation. The other wrinkle in valence bond theory that we need to mention is the conservation of orbitals. We will look at delocalisation and resonance in more detail in another summary. ![]()
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