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  2. VSEPR theory - Wikipedia

    en.wikipedia.org/wiki/VSEPR_theory

    The difference between lone pairs and bonding pairs may also be used to rationalize deviations from idealized geometries. For example, the H 2 O molecule has four electron pairs in its valence shell: two lone pairs and two bond pairs. The four electron pairs are spread so as to point roughly towards the apices of a tetrahedron.

  3. Lone pair - Wikipedia

    en.wikipedia.org/wiki/Lone_pair

    The σ-symmetry lone pair (σ(out)) is formed from a hybrid orbital that mixes 2s and 2p character, while the π-symmetry lone pair (p) is of exclusive 2p orbital parentage. The s character rich O σ(out) lone pair orbital (also notated n O (σ) ) is an ~sp 0.7 hybrid (~40% p character, 60% s character), while the p lone pair orbital (also ...

  4. Wikipedia:Reference desk/Archives/Science/2009 December 18 ...

    en.wikipedia.org/wiki/Wikipedia:Reference_desk/...

    Lone pair electrons will push away bonding electrons just as well as bonding electrons push each other away. In fact, lone pairs have a greater repulsive effect than do bonding pairs because the lone pairs are more localized around the central atom, and thus more "concentrated" and thus have a greater repulsive force associated with them.

  5. Electron pair - Wikipedia

    en.wikipedia.org/wiki/Electron_pair

    They can form a chemical bond between two atoms, or they can occur as a lone pair of valence electrons. They also fill the core levels of an atom. Because the spins are paired, the magnetic moment of the electrons cancel one another, and the pair's contribution to magnetic properties is generally diamagnetic .

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

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

    The σ-π model differentiates bonds and lone pairs of σ symmetry from those of π symmetry, while the equivalent-orbital model hybridizes them. The σ-π treatment takes into account molecular symmetry and is better suited to interpretation of aromatic molecules ( Hückel's rule ), although computational calculations of certain molecules tend ...

  7. Bent's rule - Wikipedia

    en.wikipedia.org/wiki/Bent's_rule

    [5] [22] For instance, a modification of this analysis is still viable, even if the lone pairs of H 2 O are considered to be inequivalent by virtue of their symmetry (i.e., only s, and in-plane p x and p y oxygen AOs are hybridized to form the two O-H bonding orbitals σ O-H and lone pair n O (σ), while p z becomes an inequivalent pure p ...

  8. The psychology of food aversions: Why some people don't grow ...

    www.aol.com/lifestyle/psychology-food-aversions...

    Why do food aversions happen? It depends. "One reason food aversions occur is a survival mechanism," Jennifer Carter, an associate professor of psychiatry and behavioral health at the Ohio State ...

  9. Unpaired electron - Wikipedia

    en.wikipedia.org/wiki/Unpaired_electron

    In chemistry, an unpaired electron is an electron that occupies an orbital of an atom singly, rather than as part of an electron pair. Each atomic orbital of an atom (specified by the three quantum numbers n, l and m) has a capacity to contain two electrons ( electron pair ) with opposite spins .