Final answer:
The core of the Earth is where the most dense materials are located, consisting mainly of iron and nickel. The mantle is less dense than the core, and the crust is the least dense and thinnest layer of the Earth.
Step-by-step explanation:
The most dense materials in the Earth are located in the core. The Earth's composition is divided into three main layers by their chemical properties: the crust, mantle, and the core. The core itself has an inner and an outer part, with the inner core being solid and the outer core being liquid. The inner core is thought to be composed of an iron and nickel alloy and is incredibly dense due to the immense pressure it is under. The mantle surrounds the core and is less dense, consisting mostly of rocks with a high iron and magnesium content. Finally, the Earth's crust is the outermost and thinnest layer, composed mainly of silicon and aluminum oxides, with continental crust being thicker and less dense than oceanic crust.