Kinetic momentum of quantum systems and the size of the helium atom

Aim is to correct the value of the radius of the helium atom. Methodology. A semi-classical approach is used, which is quite sufficient for the purpose of the work. Results. The need to eliminate double standards when determining the angular momentum of quantum systems leads to the fact that the quantum of angular momentum ћ is assigned not to each electron of the helium atom, but to their quantum set. The consequence of this is the correction of the value of the radius of the helium atom, which turned out to be almost four times smaller than the tabulated value. A corrected formula for the radius of the helium atom has been found: r 1,2 = [1 + (1 + 7α 2 )] a 0 /14 = 7,56∙10 –12 (м). Research implications lie in the fact that the size of the helium atom is of significant importance, in particular for membrane technologies.