Hydrogen ion as bare proton

Definition

Once hydrogen loses its electron, what remains is just a proton, a bare unit of positive charge with no electron cloud. It is the smallest thing managed directly in water treatment and among the most reactive.

Unlike calcium, sodium, chloride, sulfate, and bicarbonate, which carry electron clouds, hydrogen has none and therefore behaves unlike ordinary dissolved ions. It cannot sit still, cannot stay alone because it is bound to hydroxide by Kw, and cannot be outrun because it hops molecule to molecule. Its concentration swings by a factor of a hundred trillion across pH 0 to 14.

Related concepts

Grotthuss proton hopping · pH · Hydronium ion formation

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Part of The Blueprint of Water · 🧪 chemistry