First, the starch can react with water breaking up the high molecular starch molecules.
The viscosity is very dependent on the molecular weight (size) of the starch molecules, which tend to form small particles, called micelles.
The web sites below also show molecular diagrams of starch molecules.
The starch molecules involved are too big and complex for simple formulas.
This allows the tough starch molecules to be softened and begin to convert them to sugars.
It breaks down starch molecules into smaller glucose and maltose molecules.
The elements are C, H, and O, but this does not provide any info on the complex structure of starch molecules.
The enzymes then break up the big starch molecules and reconfigure them as fructose, smaller chains of the same elements.
Under high shear the water is squeezed out from between the starch molecules, which are able to interact more strongly.
The developing round peas produce a vital molecule, called starch-branching enzyme, which builds up complex starch molecules from sugar.