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[1] [2] [3] Introduced by Gilbert N. Lewis in his 1916 article The Atom and the Molecule, a Lewis structure can be drawn for any covalently bonded molecule, as well as coordination compounds. [4] Lewis structures extend the concept of the electron dot diagram by adding lines between atoms to represent shared pairs in a chemical bond.
The crystal structure of calcium hexaboride is a cubic lattice with calcium at the cell centre and compact, regular octahedra of boron atoms linked at the vertices by B-B bonds to give a three-dimensional boron network. [5] Each calcium has 24 nearest-neighbor boron atoms [1] The calcium atoms are arranged in simple cubic packing so that there ...
All charge-neutral boron halides violate the octet rule, hence they typically are Lewis acidic. For example, boron trifluoride (BF 3) combines eagerly with fluoride sources to give the tetrafluoroborate anion, BF 4 −. Boron trifluoride is used in the petrochemical industry as a catalyst. The halides react with water to form boric acid. [51]
The trihalides adopt a planar trigonal structure. These compounds are Lewis acids in that they readily form adducts with electron-pair donors, which are called Lewis bases. For example, fluoride (F −) and boron trifluoride (BF 3) combined to give the tetrafluoroborate anion, BF 4 −. Boron trifluoride is used in the petrochemical industry as ...
Some of the most studied examples of such Lewis acids are the boron trihalides and organoboranes: [9] BF 3 + F − → BF − 4. In this adduct, all four fluoride centres (or more accurately, ligands) are equivalent. BF 3 + OMe 2 → BF 3 OMe 2. Both BF 4 − and BF 3 OMe 2 are Lewis base adducts of boron trifluoride.
The boron group is notable for trends in the electron configuration, as shown above, and in some of its elements' characteristics. Boron differs from the other group members in its hardness, refractivity and reluctance to participate in metallic bonding. An example of a trend in reactivity is boron's tendency to form reactive compounds with ...
Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier homologues strontium and barium.
Boron trifluoride is the inorganic compound with the formula BF 3. This pungent, colourless, and toxic gas forms white fumes in moist air. It is a useful Lewis acid and a versatile building block for other boron compounds.