Chemistry Grade 12 Help|URGENT Hi, I need some help with this question. 1)Phosphorus forms PCl3 and PCl5. Nitrogen forms NCl3 but not NCl5. Explain the reason why NCl5 doesn't form? I know Phosphorus & Nitrogen are an exceptional to the octet rule but I don't know why NCl5 doesn't form. 2) If N, C and O all form sp3 hybrid orbitals, what reason can you give for NH3 and H2O being polar while CH4 is not. I don't even know where to start. please help. If you need me to rephase the question, please comment. Also, a link to a site which could help me would be more than helpful.