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|Section2= |Section3= |Section5= |Section6= |Section7= }} Triplet oxygen, systematically but less commonly, ''1,2-dioxidanediyl'', is a term that refers to normal, gaseous oxygen (O2, dioxygen) in its ground state. It is therefore classified as an inorganic chemical, and more specifically as a particular electronic state of one allotrope of the inorganic chemical element, oxygen. In this particular state, according to one type of modern bonding theory, the electron configuration of the oxygen molecule has two electrons occupying two molecular orbitals (MOs) of equal energy (that is, degenerate MOs), therefore remaining unpaired. These orbitals are classified as antibonding and are of higher energy, so the resulting bonding structure between the oxygen atoms is weakened (i.e., is higher in energy)—for instance, it is higher in energy than the bonding in dinitrogen, where bonding MOs are filled instead. The spectroscopic molecular term symbol for triplet (ground state) oxygen is 3Σg−.〔Atkins, Peter; Julio de Paula & Ronald Friedman (2009) ''Quanta, Matter, and Change: A Molecular Approach to Physical Chemistry,'' pp. 341-342, Oxford, GBR:Oxford University Press, ISBN 0199206066, see (). accessed 11 August 2015.〕〔Christian Hill, 2015, "Molecular Term Symbols," self-published, from Post-Doctoral Research Associate at the Department of Physics and Astronomy, University College London, see (), accessed 11 August 2015.〕 ==Spin== The s=1/2 spins of the two electrons in degenerate orbitals gives rise to 2x2=4 independent spin states in total. Exchange interaction splits these into a singlet state (total spin S=0) and a set of 3 degenerate triplet states (S=1). In agreement with Hund's rules, the triplet states are energetically more favorable, and the ground state of the molecule carries an electron spin of S=1. Excitation to the S=0 state results in much more reactive, metastable singlet oxygen. Because the molecule in its ground state has a non-zero spin magnetic moment, oxygen is paramagnetic; i.e., it can be attracted to the poles of a magnet. The Lewis structure O=O does not accurately represent the diradical nature of molecular oxygen; molecular orbital theory must be used to adequately account for the unpaired electrons. Triplet oxygen is better described by a bond order of one and two halves instead of two to better reflect its unpaired bonding electrons. This allows for easier reasoning of the bond length. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「triplet oxygen」の詳細全文を読む スポンサード リンク
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