Triplet oxygen

Other names: dioxidanediyl, dioxygen(2•)(triplet), oxygen

³O₂

30/50 common

Triplet oxygen is the ground state "electronic isomer" of molecular oxygen (O₂) that we breathe every day. This S=1 spin state contains two unpaired electrons with parallel spins, making oxygen a diradical and giving it paramagnetic properties. Unlike most stable molecules, triplet oxygen violates the standard octet rule, creating a paradoxical situation: it's simultaneously reactive yet kinetically stable, due to the conservation of spin. Paradoxically, its closed-shell singlet excited state, as drawn by high-school chemistry students across the world, is a far less happy molecule.