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  2. Valence electron - Wikipedia

    en.wikipedia.org/wiki/Valence_electron

    In chemistry and physics, valence electrons are electrons in the outermost shell of an atom, and that can participate in the formation of a chemical bond if the outermost shell is not closed. In a single covalent bond, a shared pair forms with both atoms in the bond each contributing one valence electron. The presence of valence electrons can ...

  3. d electron count - Wikipedia

    en.wikipedia.org/wiki/D_electron_count

    The d electron count or number of d electrons is a chemistry formalism used to describe the electron configuration of the valence electrons of a transition metal center in a coordination complex. [1][2] The d electron count is an effective way to understand the geometry and reactivity of transition metal complexes.

  4. Aufbau principle - Wikipedia

    en.wikipedia.org/wiki/Aufbau_principle

    An example is the configuration 1s 2 2s 2 2p 6 3s 2 3p 3 for the phosphorus atom, meaning that the 1s subshell has 2 electrons, and so on. The configuration is often abbreviated by writing only the valence electrons explicitly, while the core electrons are replaced by the symbol for the last previous noble gas in the periodic table, placed in ...

  5. Electron configuration - Wikipedia

    en.wikipedia.org/wiki/Electron_configuration

    Electron configuration. In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. [1] For example, the electron configuration of the neon atom is 1s2 2s2 2p6, meaning that the 1s, 2s, and 2p subshells are occupied by ...

  6. 18-electron rule - Wikipedia

    en.wikipedia.org/wiki/18-electron_rule

    The 18-electron rule is a chemical rule of thumb used primarily for predicting and rationalizing formulas for stable transition metal complexes, especially organometallic compounds. [1] The rule is based on the fact that the valence orbitals in the electron configuration of transition metals consist of five (n −1)d orbitals, one n s orbital ...

  7. Electron counting - Wikipedia

    en.wikipedia.org/wiki/Electron_counting

    Electron counting. In chemistry, electron counting is a formalism for assigning a number of valence electrons to individual atoms in a molecule. It is used for classifying compounds and for explaining or predicting their electronic structure and bonding. [1] Many rules in chemistry rely on electron-counting:

  8. Lewis structure - Wikipedia

    en.wikipedia.org/wiki/Lewis_structure

    Count valence electrons. Nitrogen has 5 valence electrons; each oxygen has 6, for a total of (6 × 2) + 5 = 17. The ion has a charge of −1, which indicates an extra electron, so the total number of electrons is 18. Connect the atoms by single bonds. Each oxygen must be bonded to the nitrogen, which uses four electrons—two in each bond.

  9. Molecular Hamiltonian - Wikipedia

    en.wikipedia.org/wiki/Molecular_Hamiltonian

    v. t. e. In atomic, molecular, and optical physics and quantum chemistry, the molecular Hamiltonian is the Hamiltonian operator representing the energy of the electrons and nuclei in a molecule. This operator and the associated Schrödinger equation play a central role in computational chemistry and physics for computing properties of molecules ...