Calcium

About Calcium

Calcium is the structural element of biology and the world's largest-tonnage industrial metal you never see as the metal. Inside cells, free Ca²⁺ sits at around 100 nM in the cytosol against ~2 mM outside — a 20,000-fold gradient that ATP-driven SERCA pumps maintain at considerable energetic cost, and that every action potential, muscle twitch, and exocytosis event briefly dumps. Outside the body, calcium chemistry is mostly the chemistry of CaCO₃ and CaSO₄. The Solvay process consumes limestone by the megaton; cement production through calcination of CaCO₃ to CaO releases roughly 8% of global anthropogenic CO₂ and is the single hardest decarbonization problem in heavy industry. In a chem lab, calcium turns up as the Lewis acid in Grignard chemistry's poor cousin (the Barbier reaction with Ca turnings), as a CaCl₂ desiccant in the bench drying tower, and as the calcium standard in EDTA titrations of water hardness. The metal itself, distilled from CaO with aluminum, is silvery, soft, and reactive enough that you store it under mineral oil.