What physical property of lead makes it effective for radiation shielding?

The effectiveness of lead as a radiation shielding material is primarily due to its high density. High-density materials are particularly effective at attenuating radiation because they provide a greater number of atoms per unit volume for incoming radiation to interact with. This interaction can result in scattering, absorption, or a combination of both, effectively reducing the intensity of the radiation that passes through the material.

In the context of shielding, the high atomic number of lead also plays a role, as it increases the likelihood of interaction with photons, such as gamma rays or X-rays. The combination of high density and high atomic number makes lead particularly useful for shielding against ionizing radiation.

While lead's conductivity and malleability can be useful characteristics in other contexts, they do not directly influence its ability to shield against radiation. Additionally, the fact that lead is a natural element provides no direct advantage in terms of its effectiveness as a shielding material compared to synthetic materials. Therefore, its high density stands out as the key property that enables lead to serve effectively in radiation protection.