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This could ease the theoretical phase diagram generation of multicomponent systems. For alloys containing transition metal elements there is a difficulty in interpretation of the Hume-Rothery electron concentration rule, as the values of e/a values (number of itinerant electrons per atom) for transition metals have been quite controversial for ...
The valence is the combining capacity of an atom of a given element, determined by the number of hydrogen atoms that it combines with. In methane, carbon has a valence of 4; in ammonia, nitrogen has a valence of 3; in water, oxygen has a valence of 2; and in hydrogen chloride, chlorine has a valence of 1.
One of Pauling's examples is olivine, M 2 SiO 4, where M is a mixture of Mg 2+ at some sites and Fe 2+ at others. The structure contains distinct SiO 4 tetrahedra which do not share any oxygens (at corners, edges or faces) with each other. The lower-valence Mg 2+ and Fe 2+ cations are surrounded by polyhedra which do share oxygens.
Pr 6 O 11 adopts a cubic fluorite crystal structure, measured by XRD, TEM and SEM methods. [3] [5] It can be considered an oxygen deficient form of praseodymium(IV) oxide (PrO 2), with the Pr ions being in a mixed valency state Pr(III) and Pr(IV). [5] This characteristic is what gives the oxide its many useful properties for its catalytic activity.
The bond-order formula at the bottom is closest to the reality of four equivalent oxygens each having a total bond order of 2. That total includes the bond of order 1 / 2 to the implied cation and follows the 8 − N rule [ 7 ] requiring that the main-group atom's bond-order total equals 8 − N valence electrons of the neutral atom ...
The data below tabulates standard electrode potentials ... and the Faraday constant F is the conversion factor describing Coulombs transferred per mole electrons ...
Ammonium iron(II) sulfate, or Mohr's salt, is the inorganic compound with the formula (NH 4) 2 SO 4 ·Fe(SO 4)·6H 2 O. Containing two different cations, Fe 2+ and NH + 4, it is classified as a double salt of ferrous sulfate and ammonium sulfate. It is a common laboratory reagent because it is readily crystallized, and crystals resist oxidation ...
The order of reactivity, as shown by the vigour of the reaction with water or the speed at which the metal surface tarnishes in air, appears to be Cs > K > Na > Li > alkaline earth metals, i.e., alkali metals > alkaline earth metals, the same as the reverse order of the (gas-phase) ionization energies.