Introduction
Over the years, selenium is known to be the essential element in all forms of life. Selenium is a metalloid belonging to the block p, group 16, period 4. It is a gray metallic rare element widely distributed within Earth’s crust which has an atomic number of 34 and a symbol “Se”.
Selenium was discovered in 1817 by Jöns Jacob Berzelius and Johan Gottlieb Gahn after analysing an impurity contaminating the sulphuric acid being produced by a factory in Sweden. The term selenium originated from the Greek word Selene, which means moon.
Selenium and tellurium tends to occur together in the Earth and have somewhat similar properties. Selenium is a naturally occurring mineral element distributed …show more content…
The ability to power solar gadgets from photocells to convert sunlight into electrical energy which is then stored in batteries has great credits to selenium. In addition, selenium has also other interesting electrical properties. Wherein, it is used in special converters or known as rectifiers to convert AC electricity to DC …show more content…
It reduces the amount of heat that enters the building from the sunlight when it is used on the specialized glass sheet for windows. It also serves as a decolorizing agent in the glass industry. Other variety of applications of selenium include: as a component of pigments in plastics, paints, enamels, inks, and rubber; pesticide formulations; as a constituent of fungicides; for toning of photographs; radioactive selenium used for diagnostic medicine.
Nevertheless, the main point why selenium is being considered as the essential element is because it plays a key role in the metabolism. Its applications for all forms of life include: as a nutritional supplement, in the preparation of pharmaceuticals and as a nutritive feed for poultry and livestock.
Selenium Physical and Atomic Properties
A number of selenium exists with different physical and chemical properties. For that reason, selenium exists in a number of allotropic forms. There are two main allotropes of selenium, one is an amorphous red powder and the other is a bluish with a metallic appearance. Further number of Selenium allotropes has properties somewhere between the two allotropes.
The amorphous forms of selenium may change from one colour and texture to another. It also do not have specific melting point. The table below summarizes the physical properties of selenium.
Table 1. Physical Properties of Selenium
Phase Solid
Density (gray) 4.81