IDK if you can reply to this, but does the pi bond attached to the Oxygen count as a nucleophillic center as well? Or when a pi bond is on an open bond? Is there any exceptions to the pi bond rule?
When a central carbon has four carbons connected to it, that carbon's going to be neutral. That's because it has 4 valence electrons that each get paired to one from all the other carbons. Each electron that pairs with that of the carbon gives it a slight negative charge. On the other hand, taking away one carbon removes an electron that pairs with the central carbon atom. So, removing a negative charge gives you a net positive charge. That central carbon center with three single bonds then gets a full positive charge because you took out the equivalent of one electron's worth of negative charge from it. Hope that helps!