Therefore, and asked to repeat the experiments Chadwick on platinum or on the cheaper lead.

These new chemical elements 72-75 is difficult to discover through chemical properties, as if in its nucleus starts filling the inner casing protons from 1 to 4 then corresponding to these protons, electrons will be closest to the core.
  Therefore, and asked to repeat the experiments Chadwick on platinum or on the cheaper lead. If the charge of the nucleus would lead to 4 points more, you can search for items 72-75. I think that the chemical properties of the 71 will be the same as the room 75.