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Left: The dot-and-cross diagram of the LDQ structure of ozone (O 3). The nuclei are as indicated and the electrons are denoted by either dots or crosses, depending on their relative spins. Right: Simplified diagram of the LDQ structure of O 3, showing electrons in non-coincident pairs using thin lines and a coincident electron pair using a ...
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The AKF diagram is intended for rocks containing excess aluminium and silica. Its components are: A = Al 2 O 3 - (CaO + Na 2 O + K 2 O) K = K 2 O F = FeO + MgO + MnO. This diagram is less useful, because magnesium does not freely substitute for ferrous iron in many metamorphic minerals important in aluminium-rich rock.
[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.
Figure 1: L 3 - and L 2-edges of [CuCl 4] 2−. Metal L-edge spectroscopy is a spectroscopic technique used to study the electronic structures of transition metal atoms and complexes . This method measures X-ray absorption caused by the excitation of a metal 2p electron to unfilled d orbitals (e.g. 3d for first-row transition metals), which ...
Cubic γ-Al 2 O 3 has important technical applications. The so-called β-Al 2 O 3 proved to be NaAl 11 O 17. [18] Molten aluminium oxide near the melting temperature is roughly 2/3 tetrahedral (i.e. 2/3 of the Al are surrounded by 4 oxygen neighbors), and 1/3 5-coordinated, with very little (<5%) octahedral Al-O present. [19]
BF 3 + OMe 2 → BF 3 OMe 2. Both BF 4 − and BF 3 OMe 2 are Lewis base adducts of boron trifluoride. Many adducts violate the octet rule, such as the triiodide anion: I 2 + I − → I − 3. The variability of the colors of iodine solutions reflects the variable abilities of the solvent to form adducts with the Lewis acid I 2.
CALPHAD stands for Computer Coupling of Phase Diagrams and Thermochemistry, a methodology introduced in 1970 by Larry Kaufman, originally known as CALculation of PHAse Diagrams. [1] [2] [3] An equilibrium phase diagram is usually a diagram with axes for temperature and composition of a chemical system. It shows the regions where substances or ...