Final answer:
An alloy is a homogeneous mixture containing at least one metal, with uniform composition throughout. Examples include steel, brass, and bronze. Alloys are categorized as substitutional or interstitial based on their atomic arrangements.
Step-by-step explanation:
An alloy is best defined as a homogeneous mixture of two or more elements, where at least one of the elements is a metal. The composition of an alloy is uniform throughout, making it a single substance in appearance and properties. For instance, steel is an alloy containing mainly iron and a small amount of carbon, with other elements such as manganese and chromium added for improved strength and resistance to rust, respectively.
Alloys are classified into two main types: substitutional, where different atoms replace each other in the crystal structure, and interstitial, where smaller atoms fit between larger atoms in the crystal packing arrangement. This means that in contrast to heterogeneous mixtures, which have non-uniform composition and visible different components, alloys are consistent and even in their physical makeup.