Recently I begun learning about molecular orbitals and the geometry of an sp orbital. It is my understanding that in the creation of an sp orbital with the combination of an s orbital and p orbital, one gets something that resembles half of a p-orbital (although larger). My professor noted that the other lobe exists infinitesimally small, in opposite phase. She said it was beyond the scope of our course to discuss how this lobe would affect the geometry of MOs, but I was curious regardless. When I asked her she said she would get back to me, and hasn't yet, so I thought I'd ask around on my own! Why/when do these infinitesimally small lobes affect the geometry of an MO? Probabilistically speaking, what is the math behind it? Basically, if anyone knows anything about the relationship/importance of maintaining the infinitesimally small lobe of an sp-orbital, do tell! Thanks, I look forward to hearing from you!