Chemistry 2720 Fall 1999 Quiz 10 Solution

Homonuclear diatomic molecules with up to 8 electrons only use the MOs derived from the 1s and 2s atomic orbitals. Thus, none of the molecules , , or can be paramagnetic. has ten electrons, so two of these electrons occupy the orbital (one electron in each orbital) and so this molecule is paramagnetic. has full orbitals and has a highest occupied molecular orbital (HOMO) so neither of these is paramagnetic. is paramagnetic because its last two electrons are placed in the antibonding orbitals. Both and have filled HOMOs so neither of these is paramagnetic. Thus, just two of this series of molecules are paramagnetic: and .