Search results
Results From The WOW.Com Content Network
Aluminium sulfate is rarely, if ever, encountered as the anhydrous salt. It forms a number of different hydrates, of which the hexadecahydrate Al 2 (SO 4) 3 ·16H 2 O and octadecahydrate Al 2 (SO 4) 3 ·18H 2 O are the most common. The heptadecahydrate, whose formula can be written as [Al(H 2 O) 6] 2 (SO 4) 3 ·5H 2 O, occurs naturally as the ...
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 .
[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.
Lewis structure is best used to calculate formal charges or how atoms bond to each other as both electrons and bonds are shown. Lewis structures give an idea of the molecular and electronic geometry which varies based on the presence of bonds and lone pairs and through this one could determine the bond angles and hybridization as well.
At higher temperature, the Al(III) centers become randomized to give a "defect wurtzite" structure. And at still higher temperatures stabilize the γ-Al 2 S 3 forms, with a structure akin to γ-Al 2 O 3. Molecular derivatives of Al 2 S 3 are not known. Mixed Al-S-Cl compounds are however known. Al 2 Se 3 and Al 2 Te 3 are also known.
3 · n H 2 O , which is used for most industrial flocculation [ 1 ] : 766 (the variable n is an integer whose size depends on the amount of water absorbed into the alum). For medicine , the word "alum" may also refer to aluminium hydroxide gel used as a vaccine adjuvant .
This would result in the geometry of a regular tetrahedron with each bond angle equal to arccos(− 1 / 3 ) ≈ 109.5°. However, the three hydrogen atoms are repelled by the electron lone pair in a way that the geometry is distorted to a trigonal pyramid (regular 3-sided pyramid) with bond angles of 107°.
2 Al(CH 3) 3 + 3 H 2 O → Al 2 O 3 + 6 CH 4. H 2 O in the above reaction can be replaced by ozone (O 3) as the active oxidant and the following reaction then takes place: [44] [45] 2 Al(CH 3) 3 + O 3 → Al 2 O 3 + 3 C 2 H 6. The Al 2 O 3 films prepared using O 3 show 10–100 times lower leakage current density compared with those prepared by ...