Which is harder, steel or gold? The answer is steel. Steel is significantly harder than gold. This is due to the differences in their composition and atomic structures. Gold has a Mohs hardness of 2.5 to 3, which is relatively soft compared to steel. The Mohs scale is a qualitative measure of mineral hardness, with diamond being the hardest at 10 and talc being the softest at 1. In contrast, steel, which is an alloy of iron and carbon, can have a hardness ranging from 50 to 65 on the Mohs scale, depending on the specific type and composition of the steel.

The hardness of steel is primarily attributed to the presence of carbon atoms within the iron lattice. Carbon atoms disrupt the regular arrangement of iron atoms, creating a more rigid and resistant structure. This phenomenon is known as solid solution strengthening. Additionally, the formation of iron carbides, such as cementite (Fe3C), further enhances the hardness of steel. These carbides are extremely hard and contribute to the overall strength of the material.

Gold, on the other hand, is a pure metal with a relatively simple atomic structure. It lacks the complex alloying elements and interstitial atoms found in steel, which contribute to its softness. Gold's atomic structure consists of a face-centered cubic (FCC) lattice, which is less rigid and more malleable than the body-centered cubic (BCC) lattice found in steel. This allows gold to be easily deformed under pressure, making it suitable for use in jewelry and electronics but not for applications requiring high strength and durability.

Data from the Mohs scale of hardness further supports the assertion that steel is harder than gold. The Mohs scale values mentioned earlier provide a clear comparison between the two materials. Additionally, the Vickers hardness test, which measures the hardness of materials by indenting them with a diamond indenter, also confirms the higher hardness of steel. For example, a typical mild steel can have a Vickers hardness of around 200-300 MPa, whereas gold typically has a Vickers hardness of around 30-50 MPa.

In conclusion, steel is harder than gold due to its complex alloying elements, carbon content, and atomic structure. These factors contribute to the increased strength and durability of steel, making it a preferred material for various industrial and construction applications. Gold, while valuable and malleable, lacks the hardness required for such applications and is more suited for decorative and electronic uses.