Search results
Results from the WOW.Com Content Network
Diamond and graphite are two allotropes of carbon: pure forms of the same element that differ in crystalline structure.. Allotropy or allotropism (from Ancient Greek ἄλλος (allos) 'other' and τρόπος (tropos) 'manner, form') is the property of some chemical elements to exist in two or more different forms, in the same physical state, known as allotropes of the elements.
Not all elements which are found in the human body in trace quantities play a role in life. Some of these elements are thought to be simple common contaminants without function (examples: caesium, titanium), while many others are thought to be active toxins, depending on amount (cadmium, mercury, lead, radioactives).
Lonsdaleite is an allotrope sometimes called "hexagonal diamond", formed from graphite present in meteorites upon their impact on the earth. The great heat and pressure of the impact transforms the graphite into a denser form similar to diamond but retaining graphite's hexagonal crystal lattice. "Hexagonal diamond" has also been synthesized in ...
Homonuclear triatomic molecules contain three of the same kind of atom. That molecule will be an allotrope of that element. Ozone, O 3 is an example of a triatomic molecule with all atoms the same. Triatomic hydrogen, H 3, is unstable and breaks up spontaneously. H 3 +, the trihydrogen cation is stable by itself and is symmetric.
A fifth allotrope of carbon, discovered in 2003, is called graphene, and is in the form of a layer of carbon atoms arranged in a honeycomb-shaped formation. [6] [14] [15] Silicon has two known allotropes that exist at room temperature. These allotropes are known as the amorphous and the crystalline allotropes. The amorphous allotrope is a brown ...
BCC is body centered cubic and FCC is face-centered cubic. Iron-carbon eutectic phase diagram, showing various forms of Fe x C y substances. Iron allotropes, showing the differences in structure. The alpha iron (α-Fe) is a body-centered cubic (BCC) and the gamma iron (γ-Fe) is a face-centered cubic (FCC).
Although both are called "white phosphorus", in fact two different crystal allotropes are known, interchanging reversibly at 195.2 K. [5] The element's standard state is the body-centered cubic α form, which is actually metastable under standard conditions. [4] The β form is believed to have a hexagonal crystal structure. [5]
body-centered cubic : 16.51 [1] Plutonium occurs in a variety of allotropes, ... For example, the alpha (α) phase exists at room temperature in unalloyed plutonium.