21 June 2019 - oxygen 1

Why is the atmosphere full of oxygen? Because nuclear physics makes oxygen easy for stars to produce. Over half the atoms in the Earth’s crust are oxygen atoms. If you gather energy to do serious chemistry from scratch, because you are a plant and must scavenge for a living, then oxygen is a likely waste product because it is in oversupply; you must strip oxygen from molecules to get at the atoms you want. Why do we thank the living plants rather than the dead stars and the first living cell? Because we are also scavengers and see only the immediate.