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  2. VSEPR theory - Wikipedia

    en.wikipedia.org/wiki/VSEPR_theory

    The bond angle for water is 104.5°. Valence shell electron pair repulsion (VSEPR) theory (/ ˈ v ɛ s p ər, v ə ˈ s ɛ p ər / VESP-ər, [1]: 410 və-SEP-ər [2]) is a model used in chemistry to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms. [3]

  3. Valence bond theory - Wikipedia

    en.wikipedia.org/wiki/Valence_bond_theory

    The impact of valence theory declined during the 1960s and 1970s as molecular orbital theory grew in usefulness as it was implemented in large digital computer programs. Since the 1980s, the more difficult problems, of implementing valence bond theory into computer programs, have been solved largely, and valence bond theory has seen a ...

  4. Sigma-pi and equivalent-orbital models - Wikipedia

    en.wikipedia.org/wiki/Sigma-pi_and_equivalent...

    Initially, Linus Pauling's scheme of water as presented in his hallmark paper on valence bond theory consists of two inequivalent lone pairs of σ and π symmetry. [5] As a result of later developments resulting partially from the introduction of VSEPR, an alternative view arose which considers the two lone pairs to be equivalent, colloquially ...

  5. Molecular geometry - Wikipedia

    en.wikipedia.org/wiki/Molecular_geometry

    In accordance with the VSEPR (valence-shell electron pair repulsion theory), the bond angles between the electron bonds are arccos(− ⁠ 1 / 3 ⁠) = 109.47°. For example, methane (CH 4) is a tetrahedral molecule. Octahedral: Octa-signifies eight, and -hedral relates to a face of a solid, so "octahedral" means "having eight faces". The bond ...

  6. Orbital hybridisation - Wikipedia

    en.wikipedia.org/wiki/Orbital_hybridisation

    Chemist Linus Pauling first developed the hybridisation theory in 1931 to explain the structure of simple molecules such as methane (CH 4) using atomic orbitals. [2] Pauling pointed out that a carbon atom forms four bonds by using one s and three p orbitals, so that "it might be inferred" that a carbon atom would form three bonds at right angles (using p orbitals) and a fourth weaker bond ...

  7. Bent's rule - Wikipedia

    en.wikipedia.org/wiki/Bent's_rule

    According to VSEPR theory, diethyl ether, methanol, water and oxygen difluoride should all have a bond angle of 109.5 o. [12] Using VSEPR theory, all these molecules should have the same bond angle because they have the same "bent" shape. [12] Yet, clearly the bond angles between all these molecules deviate from their ideal geometries in ...

  8. Lone pair - Wikipedia

    en.wikipedia.org/wiki/Lone_pair

    Thus, the number of electrons in lone pairs plus the number of electrons in bonds equals the number of valence electrons around an atom. Lone pair is a concept used in valence shell electron pair repulsion theory (VSEPR theory) which explains the shapes of molecules. They are also referred to in the chemistry of Lewis acids and bases. However ...

  9. Molecular orbital theory - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital_theory

    Valence bond theory; Coulson–Fischer theory Generalized valence bond Modern valence bond theory: Molecular orbital theory; Hartree–Fock method Semi-empirical quantum chemistry methods Møller–Plesset perturbation theory Configuration interaction Coupled cluster Multi-configurational self-consistent field Quantum chemistry composite methods