Molecular orbital theory anti bonding

As predicted by molecular orbital theory dioxygen has two unpaired electrons and some of its chemistry shows diradical characteristics in particular, it reacts readily with other radicals. Singlet oxygen is an excited state in which the two electrons in the p anti-bonding orbitals have paired spins. It produced in some chemical reactions and has different chemical reactivity. 

Group theory was used to define the orbitals of the dihydrogen molecule. This led to the molecular orbital diagram for H2 and the relative energies of atomic, bonding and anti-bonding orbitals. 

Modern bonding theory treats the electron pairing in terms of the interaction of electron (atomic) orbitals and describes the covalent bond in terms of both bonding and anti-bonding molecular orbitals. 

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