why is there a corrlarelation between the density of metals and their location in the interior of the earth
Answers
The Earth has been a molten blob several times in its infancy.
Gravity causes heavier (more dense) compounds and elements to sink toward the center of the earth. They are not as buoyant as are silicon compounds in the crust and the almost molten (plastic) mantel.
The crushing pressure at our planet’s center causes iron (and nickel) to be a dense solid, surrounded by a molten core of slightly less dense material that has a different physical molecular structure. In the molten core are elements such as thorium and uranium which are very ‘heavy’ but lighter than the solid core. These two elements probably participate in producing fission heat needed to maintain a high temperature at the core and cause convection currents of magma in the mantel that drive plate tectonic movements at the surface.
There are no short term half-lived (less than a few 100 million years), highly radioactive isotopes remaining that could participate in heating the core.