Why did iron and nickel sink toward the center of early Earth?

During the early formation of Earth, the planet underwent a process known as differentiation, which resulted in the segregation of materials based on their density and chemical properties.12

As Earth grew through the accretion of planetesimals, it was heated by several factors, including the decay of radioactive isotopes, the impact of planetary bodies, and the gravitational energy released by the sinking of metals. This heat caused the interior of the planet to partially melt. Because metallic fragments—primarily iron and nickel—were denser than the surrounding rocky silicate material, they sank toward the center of the planet under the influence of gravity.1234

This accumulation of dense metallic liquids at the center formed Earth's core, while lighter, less-dense materials rose toward the surface to form the crust. This separation was a fundamental step in establishing the planet's internal structure.12