Bond energy and bond length can be measured bond

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Unformatted text preview: ond order is calculated from the molecular orbital energy diagram (bond order is the difference between the number of bonding electrons and the number of antibonding electrons divided by two). Paramagnetic: a kind of induced magnetism, associated with unpaired electrons, that causes a substance to be attracted into an inducing magnetic field. Diamagnetic: a type of induced magnetism, associated with paired electrons, that causes a substance to be repelled from the inducing magnetic field. The key is that paramagnetic substances have unpaired electrons in the molecular orbital diagram, whereas diamagnetic substances have only paired electrons in the MO diagram. To determine the type of magnetism, measure the mass of a substance in the presence and absence of a magnetic field. A substance with unpaired electrons will be attracted by the magnetic field, giving an apparent increase in mass in the presence of the field. A greater number of unpaired electrons will give a greater attraction and a greater observed mass increase. A diamagnetic species will not be attracted by a magnetic field and will not show a mass increase (a slight mass decrease is observed for diamagnetic species). 36. Considering only the 12 valence electrons in O2, the MO models would be: $2p* ! ! !" !" # 2p* !" # 2p !" !" !" $2p !" !" * $2s !" !" $2s !" O2 ground state Arrangement of electrons consistent with the Lewis structure (double bond and no unpaired electrons). It takes energy to pair electrons in the same orbital. Thus the structure with no unpaired electrons is at a higher energy; it is an excited state. CHAPTER 14 COVALENT BONDING: ORBITALS 583 38. The localized electron model does not deal effectively with molecules containing unpaired electrons. We can draw all of the possible structures for NO with its odd number of valence electrons but still not have a good feel for whether the bond in NO is weaker or stronger than the bond in NO−. MO theory can h...
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This note was uploaded on 01/26/2014 for the course CHEM 001 taught by Professor Giancoli during the Fall '12 term at UPenn.

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