Boron is the lightest element having an electron in a p-orbital in its ground state. But, unlike most other p-elements, it rarely obeys the octet rule and usually places only six electrons (in three molecular orbitals) onto its valence shell. Boron is the prototype for the Boron group (the IUPAC group 13). However, the other members of this group are metals and more typical p-elements (only aluminum, to some extent, shares boron's aversion to the octet rule). In the most familiar compounds, boron has the formal oxidation state III. These include oxides, sulfides, nitrides, and halides. The trihalides adopt a planar trigonal structure. These compounds are Lewis acids in that they readily form adducts with electron-pair donors called Lewis bases. For example, fluoride (F−) and boron trifluoride (BF3) combined to give the tetrafluoroborate anion BF4−. Boron trifluoride is used in the petrochemical industry as a catalyst. The halides react with water to form boric acid. It is found in nature on Earth almost entirely as various B(III) oxides, often associated with other elements. More than one hundred borate minerals contain boron in an oxidation state +3. These minerals resemble silicates in some respect, although it is often found in tetrahedral coordination with oxygen and a trigonal planar configuration. Unlike silicates, boron minerals never contain a coordination number greater than four. A typical motif is exemplified by the tetraborate anions of the common mineral borax, shown at left. The formal negative charge of the tetrahedral borate center is balanced by metal cations in the minerals, such as the sodium (Na+) in borax. The tourmaline group of borate-silicates is also a fundamental boron-bearing mineral group, and some borosilicates are also known to exist naturally. If you are looking for high quality, high purity, and cost-effective boron, or if you require the latest price, please email contact mis-asia.