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  2. Hume-Rothery rules - Wikipedia

    en.wikipedia.org/wiki/Hume-Rothery_rules

    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 ...

  3. List of chemistry mnemonics - Wikipedia

    en.wikipedia.org/wiki/List_of_chemistry_mnemonics

    The order of sequence of atomic orbitals (according to Madelung rule or Klechkowski rule) can be remembered by the following. [2] Order in which orbitals are arranged by increasing energy according to the Madelung rule. Each diagonal red arrow corresponds to a different value of n + l.

  4. Valence (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Valence_(chemistry)

    Thus, each sulfur atom is hexavalent or has valence 6, but has oxidation state +5. In the dioxygen molecule O 2, each oxygen atom has 2 valence bonds and so is divalent (valence 2), but has oxidation state 0. In acetylene H−C≡C−H, each carbon atom has 4 valence bonds (1 single bond with hydrogen atom and a triple bond with the other ...

  5. Bond valence method - Wikipedia

    en.wikipedia.org/wiki/Bond_valence_method

    The bond valence method or mean method (or bond valence sum) (not to be mistaken for the valence bond theory in quantum chemistry) is a popular method in coordination chemistry to estimate the oxidation states of atoms. It is derived from the bond valence model, which is a simple yet robust model for validating chemical structures with ...

  6. Pauling's rules - Wikipedia

    en.wikipedia.org/wiki/Pauling's_rules

    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.

  7. Oxidation state - Wikipedia

    en.wikipedia.org/wiki/Oxidation_state

    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 ...

  8. Valence bond theory - Wikipedia

    en.wikipedia.org/wiki/Valence_bond_theory

    [6] Linus Pauling published in 1931 his landmark paper on valence bond theory: "On the Nature of the Chemical Bond". Building on this article, Pauling's 1939 textbook: On the Nature of the Chemical Bond would become what some have called the bible of modern chemistry. This book helped experimental chemists to understand the impact of quantum ...

  9. Equivalent weight - Wikipedia

    en.wikipedia.org/wiki/Equivalent_weight

    In chemistry, equivalent weight (more precisely, equivalent mass) is the mass of one equivalent, that is the mass of a given substance which will combine with or displace a fixed quantity of another substance.