Why are alpha particles less penetrating than beta particles?

Alpha particles are less penetrating than beta particles primarily due to their significantly larger mass and higher electric charge.12

As Ernest Rutherford observed, alpha particles—which consist of two protons and two neutrons—are much more massive than the electrons that constitute beta particles. Because of this greater mass and their double positive charge, alpha particles interact much more intensely with the electrons in any material they pass through via the Coulomb force. This interaction acts like a "viscous drag," causing the alpha particle to deposit its energy very densely along a short path, bringing it to a stop quickly.1324

In contrast, beta particles have a much smaller mass and only a single unit of charge. Because they are so much lighter, they are less affected by the material they traverse and can travel significantly further—often 100 times the distance of an alpha particle with equivalent initial energy—before being stopped. Consequently, alpha particles are classified as high dE/dx (energy loss) radiation, while beta particles are considered low dE/dx radiation.524