O2: Oxygen Gas

Two oxygen atoms, six valence electrons each Two more needed to complete the outer shell Double bond forms, one sigma bond plus one pi Twenty one percent of every breath you take Colorless, odorless, riding on the wind Two unpaired electrons spin the same direction Paramagnetic, pulled toward a magnet's pole Pour it liquid, cold enough it turns pale blue Hang it near a magnet, watch it lift and cling Every cell burns sugar, needs this gas to work Mitochondria trade it for a spark of energy Match struck, flame fed, O2 feeds the fire Ozone forms above us, three atoms bonded together Down here we breathe the two-atom form instead Twenty one percent, steady since plants began Photosynthesis split water, set this oxygen free Two atoms, one bond, circling the whole earth O2, paired forever, carried on the wind

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Key Concepts: Two oxygen atoms share a double bond (one sigma, one pi) | Two unpaired electrons in antibonding orbitals make O2 paramagnetic (liquid O2 clings to a magnet, a real demonstration) | O2 is 21% of the atmosphere, essential for aerobic respiration and combustion | Ozone (O3) is a different, three-atom form found higher in the atmosphere | Companion to "Two Oxyas Make O2"

Key Words: double bond, sigma, pi, paramagnetic, unpaired electrons, ozone, O2

Production note (round structure): lines 1-9 as Part A, lines 10-18 entering in canon as Part B, layering through to a unison close on the final two lines.