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  2. Hydrogen bond - Wikipedia

    en.wikipedia.org/wiki/Hydrogen_bond

    Consequently, hydrogen bonds between or within solute molecules dissolved in water are almost always unfavorable relative to hydrogen bonds between water and the donors and acceptors for hydrogen bonds on those solutes. [44] Hydrogen bonds between water molecules have an average lifetime of 10 −11 seconds, or 10 picoseconds. [45]

  3. Conjugated system - Wikipedia

    en.wikipedia.org/wiki/Conjugated_system

    The energy of stabilization is known as the resonance energy when formally defined as the difference in energy between the real chemical species and the hypothetical species featuring localized π bonding that corresponds to the most stable resonance form. [6] This energy cannot be measured, and a precise definition accepted by most chemists ...

  4. Resonance (chemistry) - Wikipedia

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

    Contributing structures of the carbonate ion. In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or forms, [1] also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory.

  5. Electronic effect - Wikipedia

    en.wikipedia.org/wiki/Electronic_effect

    The structure, properties, and reactivity of a molecule are dependent on straightforward bonding interactions including covalent bonds, ionic bonds, hydrogen bonds, and other forms of bonding. This bonding supplies a basic molecular skeleton that is modified by repulsive forces generally considered steric effects. Basic bonding and steric ...

  6. Mesomeric effect - Wikipedia

    en.wikipedia.org/wiki/Mesomeric_effect

    In chemistry, the mesomeric effect (or resonance effect) is a property of substituents or functional groups in a chemical compound. It is defined as the polarity produced in the molecule by the interaction of two pi bonds or between a pi bond and lone pair of electrons present on an adjacent atom. [ 1 ]

  7. Förster resonance energy transfer - Wikipedia

    en.wikipedia.org/wiki/Förster_resonance_energy...

    Cartoon diagram of the concept of Förster resonance energy transfer (FRET). Förster resonance energy transfer is named after the German scientist Theodor Förster. [9] When both chromophores are fluorescent, the term "fluorescence resonance energy transfer" is often used instead, although the energy is not actually transferred by fluorescence.

  8. Conjugate variables (thermodynamics) - Wikipedia

    en.wikipedia.org/wiki/Conjugate_variables...

    Just as a small increment of energy in a mechanical system is the product of a force times a small displacement, so an increment in the energy of a thermodynamic system can be expressed as the sum of the products of certain generalized "forces" which, when unbalanced, cause certain generalized "displacements" to occur, with their product being the energy transferred as a result.

  9. Chemical bond - Wikipedia

    en.wikipedia.org/wiki/Chemical_bond

    Covalent bonding of two hydrogen atoms to form a hydrogen molecule, H 2. In (a) the two nuclei are surrounded by a cloud of two electrons in the bonding orbital that holds the molecule together. (b) shows hydrogen's antibonding orbital, which is higher in energy and is normally not occupied by any electrons.