Hey guys. We started learning about orbital hybridisation and the molecular orbital theory and such several days ago. Sure, I can figure out some structures hybridization, but some I can't. I think it's because I don't get the how or why some "p" level orbitals remain unchanged in hybrids such as "sp" and "sp2" (sorry don't know how to do subscripts), and then moving on to the theoretical hybridization of phosphate, which would be "sp2d." By the point where I'm trying to figure out what the hybridization of phosphate is, I'm completely lost. If you guys can help explain this, that would be great. I looked at the power-point of constructing Lewis Diagrams and I still don't really get the promotion of electrons or why "p" level orbitals remain unchanged. This might be the roadblock I need to get past in order to further understand. Or maybe it's the sigma + pi bonds I'm not quite getting. Any help or suggestions would be greatly appreciated. Thanks.