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  2. Double bond - Wikipedia

    en.wikipedia.org/wiki/Double_bond

    In a skeletal formula, a double bond is drawn as two parallel lines (=) between the two connected atoms; typographically, the equals sign is used for this. [1] [2] Double bonds were introduced in chemical notation by Russian chemist Alexander Butlerov. [citation needed] Double bonds involving carbon are stronger and shorter than single bonds.

  3. Carbonyl α-substitution reaction - Wikipedia

    en.wikipedia.org/wiki/Carbonyl_α-substitution...

    Because their double bonds are electron rich, enols behave as nucleophiles and react with electrophiles in much the same way that alkenes do. But because of resonance electron donation of a lone pair of electrons on the neighboring oxygen , enols are more electron- rich and correspondingly more reactive than alkenes.

  4. Multiplicity (chemistry) - Wikipedia

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

    Each has two electrons of opposite spin in the π* level so that S = 0 and the multiplicity is 2S + 1 = 1 in consequence. In the first excited state, the two π* electrons are paired in the same orbital, so that there are no unpaired electrons. In the second excited state, however, the two π* electrons occupy different orbitals with opposite spin.

  5. Hund's rule of maximum multiplicity - Wikipedia

    en.wikipedia.org/wiki/Hund's_Rule_of_Maximum...

    For example, the nitrogen atom ground state has three unpaired electrons of parallel spin, so that the total spin is 3/2 and the multiplicity is 4. The lower energy and increased stability of the atom arise because the high-spin state has unpaired electrons of parallel spin, which must reside in different spatial orbitals according to the Pauli ...

  6. Linnett double-quartet theory - Wikipedia

    en.wikipedia.org/wiki/Linnett_Double-Quartet_Theory

    “By allowing the two electrons independent ‘movement’ in a three-centre system, the three-centre bond allows the electrons a fairly considerable chance of being near one another”. Similarly, the resonance forms shown above also increase the degree of inter-electronic repulsions as the electrons are paired up in the boron-hydrogen bonds.

  7. Bond order - Wikipedia

    en.wikipedia.org/wiki/Bond_order

    In molecules which have resonance or nonclassical bonding, bond order may not be an integer.In benzene, the delocalized molecular orbitals contain 6 pi electrons over six carbons, essentially yielding half a pi bond together with the sigma bond for each pair of carbon atoms, giving a calculated bond order of 1.5 (one and a half bond).

  8. How to Introduce Dogs: The Best Trainer-Approved Method - AOL

    www.aol.com/lifestyle/introduce-dogs-best...

    8. Off-Leash Contact. If the on-leash contact went well, on another day, it may be possible to introduce the dogs off-leash in a neutral and safely fenced area after the next parallel walk.

  9. Molecular orbital diagram - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital_diagram

    The σ from the 2p is more non-bonding due to mixing, and same with the 2s σ. This also causes a large jump in energy in the 2p σ* orbital. The bond order of diatomic nitrogen is three, and it is a diamagnetic molecule. [12] The bond order for dinitrogen (1σ g 2 1σ u 2 2σ g 2 2σ u 2 1π u 4 3σ g 2) is three because two electrons are now ...