I was just introduced to the concept of orbital hybridization. I believe I understand the idea behind it, but there is some accompanying terminology that prevents me from achieving a greater understanding.
In the following image:
I see that one of the electrons in the $2s$ orbital of carbon is promoted to one of the $2p$ orbitals. I start to get confused when hybridization occurs, simply because there are four $\ce{sp^3}$ hybrid orbitals, as also shown in this diagram:
I learned that the name $\ce{sp^3}$ comes from the combination of one s-orbital and three p-orbitals ($\ce{s + p + p + p}$), and this makes sense to me. What doesn't make sense is why each individual hybrid orbital is called an $\ce{sp^3}$ orbital. When the $\ce{2s}$ orbital, for example, becomes an $\ce{sp^3}$ orbital, why is it referred to by its combination with p-orbitals ($\ce{sp^3}$) when it was just an s-orbital before?
Could someone please offer a simple explanation that would help clear this up? Why is each individual hybrid orbital called an $\ce{sp^3}$ orbital? It seems like all four orbitals together should be called $\ce{sp^3}$, because they all make up the combination defined by $\ce{sp^3}$ ($\ce{s + p + p + p}$).