A nozzle for atomizing a liquid includes at least one Venturi tube. A Venturi tube defines a liquid flow path and has an entrance cone, an intermediate throat of diameter d.sub.n, and an exit cone having a length along the flow path to an exit port of at least about 2d.sub.n. The exit cone also has an angle of divergence that varies from 0.degree. at the throat to about 6.degree. at the exit port. As liquid with an entrained gas, preferably constituting about 10.sup.-2 to about 10.sup.-3 fractions, passes through the throat in a Venturi tube with a Reynold's number greater than about 2300, the liquid static pressure reduces and the entrained gas forms cavities that grow as the liquid passes through the exit cone. The nozzle is substantially free of any structure that could disturb the flow in the nozzle sufficiently to allow the static pressure on the liquid to rise significantly in the nozzle. When the liquid emerges from the nozzle, the liquid static pressure rises and causes the gas cavities to collapse in a zone of collapse and to produce forces that are sufficient to atomize the liquid and to break atomic, molecular and crystalline bonds in the liquid.