What is allotropy?

What is allotropy?

• A. The ability of a material to exist in two or more different physical forms
• B. The tendency to become brittle at low temperatures
• C. An element's reluctance to react with others
• D. The rate at which a metal oxidizes

Answer: (A)

Allotropy is the phenomenon where an element can exist in two or more different physical forms in the same state, due to different atomic arrangements. These forms have distinct structures and properties even though the chemical formula is the same. For example, carbon forms diamond, graphite, and other forms, each with very different structures and characteristics; oxygen also has different allotropes like O2 and O3 in the gas phase. Phosphorus and sulfur likewise have multiple allotropes with different arrangements and properties. Other descriptions refer to how a material behaves (brittleness at low temperatures, chemical reactivity, or oxidation rate) rather than the existence of distinct structural forms of the same element, so they don’t capture what allotropy describes.

Allotropy is the phenomenon where an element can exist in two or more different physical forms in the same state, due to different atomic arrangements. These forms have distinct structures and properties even though the chemical formula is the same. For example, carbon forms diamond, graphite, and other forms, each with very different structures and characteristics; oxygen also has different allotropes like O2 and O3 in the gas phase. Phosphorus and sulfur likewise have multiple allotropes with different arrangements and properties.

Other descriptions refer to how a material behaves (brittleness at low temperatures, chemical reactivity, or oxidation rate) rather than the existence of distinct structural forms of the same element, so they don’t capture what allotropy describes.