How did the formation of the Solar System influence the differences between inner and outer planets?

During the Solar System’s birth, a rotating disk of gas and dust surrounded the young Sun, and temperatures dropped sharply with distance from the Sun. Near the Sun, high temperatures boiled away light gases, so the material that formed the inner planets was mostly heavy, rocky elements, making Earth, Mars, Venus, and Mercury small and dense. Farther out, the cooler disk allowed volatile compounds like water, methane, and ammonia to condense, so the outer planets accreted huge envelopes of hydrogen and helium around solid cores, becoming gas and ice giants. Thus, the temperature gradient in the disk created the stark contrast between the rocky inner planets and the gas‑rich outer ones.