Allotropes

Differences in properties of an element's allotropes Allotropes are different structural forms of the same element and can exhibit quite different physical properties and chemical behaviours.

All carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form.

Characteristics Allotropes main Boron chunks Boron is similar to carbon in its capability to form stable covalently bonded molecular networks.

Characteristics Physical properties Tellurium has two allotropes, crystalline and amorphous.

Four allotropes of antimony are known: a stable metallic form and three metastable forms (explosive, black and yellow).

Gray Se is formed by mild heating of other allotropes, by slow cooling of molten Se, or by condensing Se vapor just below the melting point.

It has two main allotropes : at room temperature, the stable allotrope is β-tin, a silvery-white, malleable metal, but at low temperatures it transforms into the less dense grey α-tin, which has the diamond cubic structure.

It is relatively stable in air as compared to other lanthanides. citation Terbium exists in two crystal allotropes with a transformation temperature of 1289 °C between them.

It is the interaction of those allotropes with the alloying elements, primarily carbon, that gives steel and cast iron their range of unique properties.

List of allotropes Typically, elements capable of variable coordination number and/or oxidation states tend to exhibit greater numbers of allotropic forms.

Many borides and allotropes of boron contain boron B 12 icosahedron as a basic structure unit.

Native carbon occurs in two allotropes, graphite and diamond; the latter forms at very high pressure in the mantle, which gives it a much stronger structure than graphite.

Of the other discovered allotropes, carbon nanofoam is a ferromagnetic allotrope discovered in 1997.

One element can form multiple substances different by their structure; they are called allotropes of the element.

Other selenium allotropes may contain Se 6 or Se 7 rings.

Ozone cycle overview Three forms (or allotropes ) of oxygen are involved in the ozone-oxygen cycle : oxygen atoms (O or atomic oxygen), oxygen gas ( Omain or diatomic oxygen), and ozone gas ( Omain or triatomic oxygen).

Polonium has two allotropes, which are known as α-polonium and β-polonium. citation α-polonium has a cubic crystal structure and converts the rhombohedral β-polonium at 36 °C.

Rhombic sulfur is the more stable of the two allotropes.

Several allotropes of boron exist: amorphous boron is a brown powder; crystalline boron is silvery to black, extremely hard (about 9.5 on the Mohs scale ), and a poor electrical conductor at room temperature.

Sulfur has more than 20 allotropes, oxygen has nine, selenium has at least five, polonium has two, and only one crystal structure of tellurium has so far been discovered.