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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 ...
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]
Charge number (denoted z) is a quantized and dimensionless quantity derived from electric charge, with the quantum of electric charge being the elementary charge (e, constant). The charge number equals the electric charge ( q , in coulombs ) divided by the elementary charge: z = q / e .
In atomic physics, the effective nuclear charge of an electron in a multi-electron atom or ion is the number of elementary charges an electron experiences by the nucleus. It is denoted by Z eff . The term "effective" is used because the shielding effect of negatively charged electrons prevent higher energy electrons from experiencing the full ...
Xeroradiography is a type of X-ray imaging in which a picture of the body is recorded on paper rather than on film.In this technique, a plate of selenium, which rests on a thin layer of aluminium oxide, is charged uniformly by passing it in front of a scorotron. [1]
Selenium is not produced directly by nuclear fusion. [13] Selenium makes up 30 parts per billion of the universe by weight. [57] There are only 5 parts per billion of tellurium in the Earth's crust and 15 parts per billion of tellurium in seawater. [2] Tellurium is one of the eight or nine least abundant elements in the Earth's crust. [7]
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.
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]