allotropik

Allotropy is the property of certain elements to exist in two or more distinct structural forms in the same physical state. Each allotrope has a different arrangement of atoms and bonding, leading to markedly different properties such as density, hardness, electrical conductivity, and chemical reactivity. Allotropy is most common in the solid state, but it can involve gaseous forms as well. Transitions between allotropes can occur when temperature or pressure change.

Common examples include carbon, which has diamond (a three-dimensional network of sp3 bonds) and graphite (planar layers of sp2 bonds) as well as graphene, fullerenes, and amorphous carbon. Diamond is extremely hard and an insulator, while graphite conducts electricity along its planes and is much softer. Phosphorus displays white, red, and black allotropes, with white phosphorus being highly reactive and toxic, and red and black forms more stable. Sulfur exists in several allotropes, including orthorhombic and monoclinic forms of S8 rings and polymeric sulfur under certain conditions. Oxygen has O2 and the reactive O3 (ozone) allotrope, the latter being a strong oxidizer.

Allotropy is distinct from polymorphism, which describes different forms of compounds with the same chemical formula, whereas allotropy concerns different forms of elements. Understanding allotropy is important in fields such as materials science, geology, and chemistry due to its influence on material properties and reactivity.