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  2. Electron affinity - Wikipedia

    en.wikipedia.org/wiki/Electron_affinity

    The relation between the two is E ea = −ΔE(attach). However, if the value assigned to E ea is negative, the negative sign implies a reversal of direction, and energy is required to attach an electron. In this case, the electron capture is an endothermic process and the relationship, E ea = −ΔE(attach) is still valid. Negative values ...

  3. Activation energy - Wikipedia

    en.wikipedia.org/wiki/Activation_energy

    For a chemical reaction to proceed at a reasonable rate, the temperature of the system should be high enough such that there exists an appreciable number of molecules with translational energy equal to or greater than the activation energy. The term "activation energy" was introduced in 1889 by the Swedish scientist Svante Arrhenius. [3]

  4. Electron affinity (data page) - Wikipedia

    en.wikipedia.org/wiki/Electron_affinity_(data_page)

    First, as the energy that is released by adding an electron to an isolated gaseous atom. The second (reverse) definition is that electron affinity is the energy required to remove an electron from a singly charged gaseous negative ion. The latter can be regarded as the ionization energy of the –1 ion or the zeroth ionization energy. [1]

  5. Glossary of chemistry terms - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_chemistry_terms

    Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...

  6. Glossary of physics - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_physics

    A branch of physics that studies atoms as isolated systems of electrons and an atomic nucleus. Compare nuclear physics. atomic structure atomic weight (A) The sum total of protons (or electrons) and neutrons within an atom. audio frequency A periodic vibration whose frequency is in the band audible to the average human, the human hearing range.

  7. Physical chemistry - Wikipedia

    en.wikipedia.org/wiki/Physical_chemistry

    Physical chemistry is the study of macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics such as motion, energy, force, time, thermodynamics, quantum chemistry, statistical mechanics, analytical dynamics and chemical equilibria.

  8. List of common physics notations - Wikipedia

    en.wikipedia.org/wiki/List_of_common_physics...

    velocity in terms of the speed of light c: unitless beta particle: gamma: Lorentz factor: unitless photon: gamma ray: shear strain: radian heat capacity ratio: unitless surface tension: newton per meter (N/m) delta: change in a variable (e.g. ) unitless Laplace operator: per square meter (m −2)

  9. Thermodynamic activity - Wikipedia

    en.wikipedia.org/wiki/Thermodynamic_activity

    The relative activity of a species i, denoted a i, is defined [4] [5] as: = where μ i is the (molar) chemical potential of the species i under the conditions of interest, μ o i is the (molar) chemical potential of that species under some defined set of standard conditions, R is the gas constant, T is the thermodynamic temperature and e is the exponential constant.