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Selenium is a chemical element ... These detectors use amorphous selenium to capture and convert incident X-ray photons directly into electric charge. Selenium has ...
The element selenium exhibits several valence states. Selenate is the least reduced, followed by selenite, and elemental selenium; selenide is even more reduced than elemental selenium. [6] The valence state is an important factor to the toxicity of selenium. Selenate is the form required by organisms that need selenium as a micronutrient.
Selenium is toxic in high concentrations. As sodium selenite, the chronic toxic dose for human beings was described as about 2.4 to 3 milligrams of selenium per day. [7] In 2000, the US Institute of Medicine set the adult Tolerable upper intake levels (UL) for selenium from all sources - food, drinking water and dietary supplements - at 400 μg/day. [8]
It is the oxyanion of selenium. It is the selenium analog of the sulfite ion, SO 2− 3. Thus selenite is pyramidal and selenium is assigned oxidation state +4. Selenite also refers to compounds that contains this ion, for example sodium selenite Na 2 SeO 3 which is a common source of selenite. [1]
As indicated by the fact that only a few thousand tons of selenium are produced annually, the subset of selenium compounds called selenides find few applications. Commercially significant is zinc selenide, which is used in some infrared optics. Cadmium selenide is a pigment but its use has been declining because of environmental considerations.
The compound reacts with electrophiles to produce the selenium compounds. With alkyl halides, one obtains a variety of organoselenium compounds: Na 2 Se + 2 RBr → R 2 Se + 2 NaBr. Organotin and organosilicon halides react similarly to give the expected derivatives: Na 2 Se + 2 Me 3 XCl → (Me 3 X) 2 Se + 2 NaCl (X ∈ Si, Ge, Sn)
Selenium is a nutrient that is naturally present in many foods, added to others and is also available as a dietary supplement in pill, powder and liquid form, explains Perri Halperin, a ...
Chosen for its selenium content and high solubility, sodium selenate is a common ingredient in over-the-counter vitamin supplements. Selenium is a trace essential element. Sodium selenate and selenite are also common in premix animal feed. Neither compound has demonstrated a difference in the amount of selenium absorbed.