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  2. Electron counting - Wikipedia

    en.wikipedia.org/wiki/Electron_counting

    ionic counting: Fe(0) contributes 8 electrons, each CO contributes 2 each: 8 + 2 × 5 = 18 valence electrons conclusions: this is a special case, where ionic counting is the same as neutral counting, all fragments being neutral. Since this is an 18-electron complex, it is expected to be isolable compound. Ferrocene, (C 5 H 5) 2 Fe, for the ...

  3. Coordination number - Wikipedia

    en.wikipedia.org/wiki/Coordination_number

    For molecules and polyatomic ions the coordination number of an atom is determined by simply counting the other atoms to which it is bonded (by either single or multiple bonds). [1] For example, [Cr(NH 3 ) 2 Cl 2 Br 2 ] − has Cr 3+ as its central cation, which has a coordination number of 6 and is described as hexacoordinate .

  4. Octet rule - Wikipedia

    en.wikipedia.org/wiki/Octet_rule

    The bonding in carbon dioxide (CO 2): all atoms are surrounded by 8 electrons, fulfilling the octet rule.. The octet rule is a chemical rule of thumb that reflects the theory that main-group elements tend to bond in such a way that each atom has eight electrons in its valence shell, giving it the same electronic configuration as a noble gas.

  5. IUPAC numerical multiplier - Wikipedia

    en.wikipedia.org/wiki/IUPAC_numerical_multiplier

    The IUPAC numerical multiplier is a system of prefixes used in chemistry to indicate the number of atoms or groups in a molecule.

  6. Lewis structure - Wikipedia

    en.wikipedia.org/wiki/Lewis_structure

    A simpler method has been proposed for constructing Lewis structures, eliminating the need for electron counting: the atoms are drawn showing the valence electrons; bonds are then formed by pairing up valence electrons of the atoms involved in the bond-making process, and anions and cations are formed by adding or removing electrons to/from the ...

  7. Ionic bonding - Wikipedia

    en.wikipedia.org/wiki/Ionic_bonding

    Ionic bonding is a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions, or between two atoms with sharply different electronegativities, [1] and is the primary interaction occurring in ionic compounds.

  8. 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 ...

  9. Ionization energy - Wikipedia

    en.wikipedia.org/wiki/Ionization_energy

    Ionization energy trends plotted against the atomic number, in units eV.The ionization energy gradually increases from the alkali metals to the noble gases.The maximum ionization energy also decreases from the first to the last row in a given column, due to the increasing distance of the valence electron shell from the nucleus.