Chemistry · Ch 2 — p-Block Elements-I
Allotropism in p-Block Elements
Allotropism in p-Block Elements
Some elements can exist in more than one distinct crystalline or molecular form while remaining in the same physical state -- carbon, for instance, exists as both diamond and graphite, two solids with utterly different structures and properties built from exactly the same atoms. This phenomenon is called allotropism (from the Greek allos, another, and trope, change/form), and the individual forms themselves are called allotropes.
Allotropism is widespread across the p-block. Boron shows several allotropes (amorphous and various rhombohedral/tetragonal crystalline forms); carbon's allotropes include diamond, graphite, graphene, fullerenes and carbon nanotubes (explored in depth in Section 2.3.4); silicon exists as amorphous and crystalline forms; germanium and tin each have two or more distinct allotropes; phosphorus has an especially rich set (white, red, scarlet, violet and black); arsenic and antimony each show three colour forms; oxygen exists as ordinary dioxyg …
| Element | Most common allotropes |
|---|---|
| Boron | Amorphous boron, α-rhombohedral boron, β-rhombohedral boron, γ-orthorhombic boron, α-tetragonal boron, β-tetragonal boron |
| Carbon | Diamond, Graphite, Graphene, Fullerenes, Carbon nanotubes |
| Silicon | Amorphous silicon, crystalline silicon |
| Germanium | α-germanium, β-germanium |
| Tin | Grey tin, white tin, rhombic tin, sigma tin |
| Phosphorus | White phosphorus, Red phosphorus, Scarlet phosphorus, Violet phosphorus, Black phosphorus |
| Arsenic | Yellow arsenic, gray arsenic, Black arsenic |
| Antimony | Blue-white antimony, Yellow, Black |
| Oxygen | Dioxygen, ozone |