CHEM 1300 Lecture Notes - Lecture 19: Bond Order, Aufbau Principle, Pauli Exclusion Principle

• School: University of Manitoba
• Department: Chemistry
• Course: CHEM 1300
• Professor: Elena Smirnova

Document Summary

2nd principle: the bonding molecular orbital is lower in energy than the parent orbitals and the antibonding orbital is higher in energy. The syste(cid:373) is (cid:862)sta(cid:271)ilized(cid:863) whe(cid:374) ele(cid:272)tro(cid:374)s are assig(cid:374)ed to the (cid:271)o(cid:374)di(cid:374)g or(cid:271)itals. The bonding mo has electron density between the nuclei this maximizes electron-nuclei attraction and minimizes repulsion between nuclei. The syste(cid:373) is (cid:862)desta(cid:271)ilized(cid:863) when electrons are assigned to the antibonding orbitals because the energy of the system is higher. The antibonding mo has a node between the nuclei this results in greater nuclei repulsion. 3rd principle: electrons of the molecule are assigned to orbitals of successively higher e(cid:374)ergy a(cid:272)(cid:272)ordi(cid:374)g to the auf(cid:271)au pri(cid:374)(cid:272)iple a(cid:374)d hu(cid:374)d"s rule. Electrons occupy the lowest energy orbitals first. Atoms are most stable with the highest number of unpaired electrons. Bond order (bo) allows us to calculate the net amount of bonding between two atoms. (cid:1005) Bo = (cid:1006) (# electrons in bonding mos - # electrons in antibonding mos)