Chemistry 1301A/B Chapter Notes - Chapter 2: Unpaired Electron, Paramagnetism, Antibonding Molecular Orbital
20 Apr 2017
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Formation of molecular orbitals: delocalized electrons are common to the entire molecules. The bonding is based on the wave behaviour of electrons. Constructive combination occurs when 2 atomic orbitals in the same phase (either both + or -) combine. Destructive combination occurs when the 2 1s orbitals of opposite phase combine. This ge(cid:374)erates a (cid:374)ew (cid:374)ode (cid:271)etwee(cid:374) 2 (cid:374)u(cid:272)lei. This does(cid:374)"t lead to (cid:271)o(cid:374)d for(cid:373)atio(cid:374), a(cid:374)d the resulti(cid:374)g sigma*1s antibonding mo. Mo energies: each mo holds a maximum of 2 electrons, and the mo of lowest energy fills first. The principles of mo theory: the number of mos equals the number of aos, bonding mos are lower in energy than the aos from which they are made, and antibonding. Mos are higher: must obey pauli exclusion principal and hu(cid:374)d"s rule, mos form best from aos of similar emergy. Mo bond order and the stability of molecules:
