Iron is generally heavier than steel. This is because iron has a higher density than steel. The density of pure iron is approximately 7.874 g/cm³, while the density of steel, which is an alloy of iron and carbon, typically ranges from 7.75 to 8.05 g/cm³. Despite the slight difference in density, the term "steel" encompasses a wide range of compositions, and the presence of other elements can affect its density. However, on average, iron is heavier than steel due to its higher density.

The weight of a material is directly related to its density and volume. Since iron has a higher density than steel, a given volume of iron will weigh more than the same volume of steel. For example, if you have a 1 cm³ block of iron and a 1 cm³ block of steel, the iron block will weigh more. This is because the iron atoms are packed more densely together than the steel atoms, which include carbon and other elements that can disrupt the atomic structure and reduce density.

It's important to note that the term "steel" can refer to a variety of alloys, and the density of steel can vary significantly depending on its composition. For instance, stainless steel, which contains additional elements like chromium and nickel, may have a slightly lower density than carbon steel. However, even in these cases, the density of the steel is still lower than that of pure iron, making iron the heavier material when comparing equal volumes.

In summary, iron is heavier than steel due to its higher density. This is a general rule, but it's important to consider the specific composition of the steel when making precise comparisons.