Triplet oxygen

<p>Triplet oxygen, 3O2, refers to the <i>S</i> = 1 electronic <a href="/facts/Ground_state/ML7cfCug">ground state</a> of molecular oxygen (dioxygen).  Molecules of triplet oxygen contain two unpaired electrons, making triplet oxygen an unusual example of a stable and commonly encountered <a href="/facts/Diradical/gH1vrH9b">diradical</a>: it is more stable as a <a href="/facts/Triplet_state/sKNlsW1M">triplet</a> than a <a href="/facts/Singlet_state/CK39GJa4">singlet</a>. According to <a href="/facts/Molecular_orbital_theory/VJ6Kg8bI">molecular orbital theory</a>, the <a href="/facts/Electron_configuration/TQjRr22P">electron configuration</a> of triplet oxygen has two electrons occupying two π <a href="/facts/Molecular_orbital/0dP30jaa">molecular orbitals</a> (MOs) of equal energy (that is, <a href="/facts/Degenerate_energy_levels/ulrnMXTR">degenerate MOs</a>).  In accordance with <a href="/facts/Hund%27s_rules/pyyb3f6a">Hund's rules</a>, they remain <a href="/facts/Electron_pair/MENP5Gm0">unpaired</a> and spin-parallel, which accounts for the <a href="/facts/Paramagnetism/vj1SMbbp">paramagnetism</a> of molecular oxygen.  These half-filled orbitals are <a href="/facts/Antibonding/9lhLNyt3">antibonding</a> in character, reducing the overall bond order of the molecule to 2 from the maximum value of 3 that would occur when these antibonding orbitals remain fully unoccupied, as in <a href="/facts/Dinitrogen/Nf1QpGDz">dinitrogen</a>.  The <a href="/facts/Molecular_term_symbol/plQdFUQX">molecular term symbol</a> for triplet oxygen is 3Σ−g.
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Triplet oxygen open-in-new

Triplet oxygen