Describe the differences between the properties of interstitial and substitutional alloys.

Interstitial alloys have smaller atoms that fit into gaps between larger atoms, while substitutional alloys have similar-sized atoms that replace each other in the crystal lattice.

Interstitial alloys are formed when smaller atoms occupy the interstitial sites between the larger atoms in the crystal lattice. These smaller atoms do not replace the larger atoms but instead fit into the gaps between them. This results in an increase in the density of the alloy and makes it harder and stronger. Examples of interstitial alloys include steel, which is made by adding carbon to iron.

Substitutional alloys are formed when similar-sized atoms replace each other in the crystal lattice. This results in little to no change in the density of the alloy, but it can affect the properties of the alloy. For example, brass is a substitutional alloy made by replacing some of the copper atoms with zinc atoms. This makes the alloy more malleable and ductile than pure copper.

A-Level Chemistry Tutor Summary: In summary, interstitial alloys are created when smaller atoms fit into the gaps between larger ones in a crystal lattice, making the alloy denser, harder, and stronger, like steel. Substitutional alloys occur when atoms of similar size replace each other, impacting the alloy's properties without changing its density much, making it more malleable, as seen with brass