Final answer:
Lead and aluminum can be used as grid interspace material due to their capacity to absorb radiation, with lead being the most effective due to its higher electron density. Plastic is not typically used as a radiation shielding material because of its lower electron density and lesser effectiveness.
Step-by-step explanation:
The materials that may be used as grid interspace material are typically those that have the ability to absorb or reduce the transmission of radiation. Lead is well-known for its effectiveness as a radiation shield because of its high density and high atomic number, which provides a greater density of electrons. This makes lead a commonly used material in applications requiring radiation shielding, such as in x-ray machines and nuclear reactors. Aluminum, while not as dense as lead, is still commonly used in applications like overhead power lines and has some capacity to absorb radiation. However, it is less effective compared to lead. Plastic is less dense and typically not used for radiation shielding on its own due to its lower electron density and lower effectiveness in absorbing radiation.When considering the interaction of ionizing radiation with materials, we observe that the range of radiation depends on the material's electron density. Metals like lead, aluminum, and steel have high electron densities due to their atomic structures, particularly those with a face-centered cubic (FCC) solid arrangement, which includes lead and aluminum. These materials possess a cubic unit cell with atoms at all of the corners and at the centers of each face. As a result, they are more effective at absorbing radiation compared to materials with lower density, such as plastic.