Selenium - Wikipedia
Selenium forms several allotropes that interconvert with temperature changes, depending somewhat on the rate of temperature change. When prepared in chemical reactions, selenium is usually an amorphous, brick-red powder. When rapidly melted, it forms the black, vitreous form, usually sold commercially as beads. [14] .
The Sublime Element Selenium | Periodic Table| ChemTalk
Allotropes of Selenium. Selenium has three main allotropic forms: red Se, gray Se, and black Se. The normal state for the element is red Se and it appears as a red amorphous powdery substance. When heated rapidly, it becomes black Se. This vitreous allotrope is both physically brittle and lustrous.
CHAPTER 1: The Chemistry of Selenium - Royal Society of Chemistry
2015年8月10日 · Selenium is a chalcogen element with atomic number 34. Selenium’s most stable allotrope is the hexagonal and crystalline form. Three main oxidation states of selenium are found: selenide (−2), selenite (+4) and selenate (+6). Selenium’s atomic mass is 78.963 and shows six stable and twenty-four radioactive isotopes.
Chemistry of Selenium (Z=34) - Chemistry LibreTexts
2023年6月30日 · Allotropes and Physical Properties. Selenium can exist in multiple allotropes that are essentially different molecular forms of an element with varying physical properties. For example, one allotrope of selenium can be seen as an …
Science made alive: Chemistry/Elem/Elements/Se
Selenium, like sulphur, exists in different allotropic forms. At least 8 different allotropic forms of selenium are known, but these can be roughly divided in three groups. These groups are mentioned below the two pictures, which show the red and black allotropes.
Selenium - Element information, properties and uses | Periodic …
While some of the allotropic forms of selenium resemble those that we know well from study of sulphur, there are others that are different. Most important, so called gray selenium consists of long chains of atoms forming extended helical structures.
Allotropes of Nonmetallic Element Selenium
This paper summarizes the allotropes of selenium according to the historical references and the latest research results, which can be divided into five categories including vapor selenium, liquid selenium, solid selenium, nano selenium and selenium clusters.
Allotrope : Selenium
The most thermodynamically stable and the densest allotrope of selenium, which contains infinite helical chains of selenium atoms. All other forms revert to gray selenium on warming.
Allotropy of selenium nanoparticles: Colourful transition, …
2023年1月9日 · Elemental selenium (Se 0) nanomaterials undergo allotropic transition from thermodynamically-unstable to more stable phases. This process is significantly different when Se 0 nanoparticles (NPs) are produced via physico-chemical and biological pathways.
(PDF) The Chemistry of Selenium - ResearchGate
2015年8月27日 · Selenium is a chalcogen element found in nature as numerous allotropic forms, six stable isotopes, several radioactive isotopes and four oxidation states.