Search results
Results from the WOW.Com Content Network
[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.
Each fluoride is connected to two Al centers. Because of its three-dimensional polymeric structure, AlF 3 has a high melting point. The other trihalides of aluminium in the solid state differ, AlCl 3 has a layer structure and AlBr 3 and AlI 3, are molecular dimers. [16] [page needed] Also they have low melting points and evaporate readily to ...
3, formed by the reaction of aluminium and iodine [4] or the action of HI on Al metal. The hexahydrate is obtained from a reaction between metallic aluminum or aluminum hydroxide with hydrogen iodide or hydroiodic acid. Like the related chloride and bromide, AlI 3 is a strong Lewis acid and will absorb water from the
Most compounds considered to be Lewis acids require an activation step prior to formation of the adduct with the Lewis base. Complex compounds such as Et 3 Al 2 Cl 3 and AlCl 3 are treated as trigonal planar Lewis acids but exist as aggregates and polymers that must be degraded by the Lewis base. [10] A simpler case is the formation of adducts ...
The polymorphs differ in terms of the stacking of the layers. All forms of Al(OH) 3 crystals are hexagonal [disputed – discuss]: gibbsite is also known as γ-Al(OH) 3 [8] or α-Al(OH) 3 [citation needed] bayerite is also known as α-Al(OH) 3 [8] or β-alumina trihydrate [citation needed] nordstrandite is also known as Al(OH) 3 [8] doyleite
AlH 3 readily forms adducts with strong Lewis bases. For example, both 1:1 and 1:2 complexes form with trimethylamine. The 1:1 complex is tetrahedral in the gas phase, [26] but in the solid phase it is dimeric with bridging hydrogen centres, [(CH 3) 3 NAlH 2 (μ-H)] 2. [27] The 1:2 complex adopts a trigonal bipyramidal structure. [26]
This change in structure is related to the lower density of the liquid phase (1.78 g/cm 3) versus solid aluminium trichloride (2.48 g/cm 3). Al 2 Cl 6 dimers are also found in the vapour phase . At higher temperatures, the Al 2 Cl 6 dimers dissociate into trigonal planar AlCl 3 monomer , which is structurally analogous to BF 3 .
The only stable chalcogenides under normal conditions are aluminium sulfide (Al 2 S 3), selenide (Al 2 Se 3), and telluride (Al 2 Te 3). All three are prepared by direct reaction of their elements at about 1,000 °C (1,832 °F) and quickly hydrolyse completely in water to yield aluminium hydroxide and the respective hydrogen chalcogenide .