# Why do we excite electrons before hybridisation?

In case of hybridisation like $\mathrm{sp^3}$ hybridisation of carbon or nitrogen why do we excite electrons before hybridisation? Why couldn't we just mix orbitals without exciting electrons?

• The way I see it, it doesn't make any difference. Bear in mind that hybridisation is just a mathematical concept, not a physical process. – orthocresol Sep 30 '15 at 8:11
• There is nothing like sp3 hybridised isolated carbon. But you can describe the carbon in CH4 as sp3 hybridised. But you cannot say: I take elemental carbon in ground state, excite and hybridise it (whatever it means), attach four hydrogen radicals and get methane. Neither you can dissect the methane in reverse process. All this stuff is just headology. – ssavec Sep 30 '15 at 11:40

• The excited $sp^3$ state does not exist on its own. See the comments on the question. – bon Oct 25 '15 at 10:31