= Bond order
{title2=$b=(N_b-N_a)/2$}
{wiki}
In the elementary <molecular orbital theory> count, <bond order> is half the excess of <Electrons> in <bonding molecular orbitals> over those in <antibonding molecular orbitals>. Thus adding one <Electron> to a <bonding molecular orbital> raises $b$ by $1/2$, while adding one to an <antibonding molecular orbital> lowers it by $1/2$. The configurations drawn above give $1$, $1/2$, and $0$. This count summarizes net <covalent bond> occupancy; it is neither a measured <energy> nor a universal test for every kind of binding. See https://openstax.org/books/chemistry-2e/pages/8-4-molecular-orbital-theory[Chemistry 2e, 8.4: molecular orbital bond order].
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