boron
Sign in to saveBoron is a chemical element; it has symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the boron group it has three valence electrons for forming covalent bonds, resulting in many compounds such as boric acid, the mineral sodium borate, and the ultra-hard crystals of boron carbide and boron nitride.
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Boron is a chemical element that exists in two main forms: a dark, brittle, shiny solid when crystalline, or a brown powder when amorphous. It's useful because its three valence electrons allow it to form many important compounds, including boric acid, sodium borate minerals, and extremely hard materials like boron carbide and boron nitride.
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Article
49 sectionsContents
- History
- Characteristics of the element
- Isotopes
- NMR spectroscopy
- Allotropes
- Atomic structure
- Chemistry of the element
- Preparation
- Reactions of the element
- Chemical compounds
- General trends
- Halides
- Oxide derivatives
- Hydrides
- Organoboron compounds
- Nitrides
- Carbides
- Borides
- Occurrence
- Production
- Market trend
- Applications
- Boronated fiberglass
- Borosilicate glass
- Elemental boron fiber
- Boron carbide ceramic
- High-hardness and abrasive compounds
- Metallurgy
- Detergent formulations and bleaching agents
- Insecticides and antifungals
- Semiconductors
- Magnets
- Shielding and neutron absorber in nuclear reactors
- Other nonmedical uses
- Pharmaceutical and biological applications
- Research
- MgB<sub>2</sub>
- Radiation-hardened semiconductors
- Proton-boron fusion
- Enriched boron (boron-10)
- Nuclear fusion
- Neutron capture therapy
- Biological role
- In human health
- Health issues and toxicity
- See also
- Notes
- References
- External links
Boron is a chemical element; it has symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the boron group it has three valence electrons for forming covalent bonds, resulting in many compounds such as boric acid, the mineral sodium borate, and the ultra-hard crystals of boron carbide and boron nitride.
Boron is synthesized entirely by cosmic ray spallation and supernovas and not by stellar nucleosynthesis, so it is a low-abundance element in the Solar System and in the Earth's crust. It constitutes about 0.001 percent by weight of Earth's crust. It is concentrated on Earth by the water-solubility of its more common naturally occurring compounds, the borate minerals. These are mined industrially as evaporites, such as borax and kernite. The largest known deposits are in Turkey, the largest producer of boron minerals.