The chemical element boron has the atomic number 5 and the letter B in its symbol. It is a brittle, black, lustrous metalloid in the form of an amorphous brown powder and crystal. Boron, the lightest element of the boron group, has three valence electrons that allow it to form covalent bonds and produce a variety of compounds, including boric acid, sodium borate, and extremely hard crystals of boron carbide and boron nitride.
Boron is an element found in low abundance in the Solar System and Earth's crust because it is produced only by cosmic ray emission and supernovae rather than by stellar nucleosynthesis. It makes up about 0,001 percent of the shell's weight.
It makes up about 0,001 percent of the weight of the earth's crust. It is concentrated on Earth because of the borate minerals, some of its most common naturally occurring components. Evaporites such as borax and kernite are mined for industrial use. Turkey, the country that produces the most boron minerals, has the largest known deposits.
Meteoroids contain a small amount of the metalloid element boron, but apart from that, boron is not found in nature on Earth. The extremely pure element is difficult to produce on an industrial scale, due to contamination from carbon or other elements that are difficult to extract. Various forms of boron exist, including amorphous boron, which is a brown powder, and crystalline boron, which is extremely hard, silvery to black, and is a poor conductor of electricity at ambient temperature.
The element's main application is in boron filaments, which are used in various high-strength materials in a manner similar to the use of carbon fibers.
Chemical compounds are the main application for boron. Production of an additive used in fiberglass for structural materials and insulation accounts for about half of the total worldwide use. The next most popular application is high-strength, lightweight structural and heat-resistant materials made from polymers and ceramics. Borosilicate glass is preferred over normal soda-lime glass due to its increased strength and resistance to thermal shock. When sodium perborate acts as a bleach. In small quantities, it is used as reactive intermediates in the production of organic fine compounds and as a dopant in semiconductors. Some organic drugs containing boron are used or are being investigated.
Natural boron consists of two stable isotopes, one of which (boron-10) has numerous applications as a neutron-capturing agent.
Biology and boron have almost very little in common. There is no consensus that it is necessary for mammalian life. Borates are occasionally used as pesticides and have low toxicity to mammals (comparable to table salt), but dangerous to arthropods. Boron-containing organic antibiotics are well known. Although it is only required in trace amounts, it is a very important plant nutrient.
Characteristic of Boron Element
Boron is similar to carbon in its tendency to form stable molecular networks by covalent bonds. Even seemingly disordered (amorphous) boron contains normal boron icosahedra randomly linked together without long-range organization. Black, extremely hard crystalline boron with a melting point above 2000 °C. It has four main allotropes: -rhombohedral, -rhombohedral, and -tetragonal (-R and -T), -orthorhombic, and -tetragonal. All four phases are stable at ambient temperatures, but -rhombohedral is the most common and reliable. There is also the -tetragonal phase (-T), but it is very difficult to produce without major impurities.
However, the phase can be described as a rock salt type arrangement of icosahedra and B2 atom pairs. The majority of the phases are based on B12 icosahedra. It can be formed by heating to 1500-1800 °C and compressing other boron phases to 12-20 GPa; then it remains stable after removing heat and pressure. The -T phase is produced at similar pressures but at higher temperatures (between 1800 and 2200 °C). At ambient conditions, the -T and -T phases can coexist, the -T phase is more stable. Borax is a superconductor at temperatures below 160-6 K when compressed above 12 GPa, and this phase has an as yet unknown structure. In 2014, borospherene (B40 molecules with fullerene-like properties) and borophene (a putative graphene-like structure) were discovered.
Source: Wikipedia
📩 09/01/2023 15:46
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