Viscosity is defined as the ability of a substance to resist flow. In a sense, viscosity is the inverse of fluidity . Cold molasses, for example, has a higher viscosity than water because it is less fluid. The effect of temperature on viscosity is intuitive. Like most liquids, the higher the temperature, the more fluid a substance becomes, thus lowering its viscosity.
Composition plays an even greater role in determining a magma's viscosity.
Silicon, on the other hand, is the most abundant cation. Thus, the Si-O bond is the single most important factor in determining the degree of a magma's viscosity. This atomic configuration is in the shape of a tetrahedron. The radicals are therefore called silicon-oxygen tetrahedra , as shown in the diagram here. These floating tetrahedra are electrically charged compounds.