Steel is indeed made primarily of iron atoms, but its density can be attributed to its unique molecular structure and the incorporation of other elements during the steel-making process.
One key reason for the increased density of steel compared to pure iron is the presence of carbon and other alloying elements such as manganese, nickel, or chromium. When these elements are added to iron, they create a more complex, compact atomic arrangement. This results in a denser material overall.
Furthermore, the types of bonds and arrangements between the atoms differ significantly between pure iron and steel. The addition of carbon affects how the iron atoms are organized, creating a mixture that can fill space more efficiently. This tighter packing leads to increased density.
In summary, while steel is composed mainly of iron, the alloying elements and the resulting atomic structure contribute to its greater density when compared to pure iron.