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  2. Quasiperiodicity - Wikipedia

    en.wikipedia.org/wiki/Quasiperiodicity

    Quasiperiodicity is the property of a system that displays irregular periodicity. Periodic behavior is defined as recurring at regular intervals, such as "every 24 hours". [1] Quasiperiodic behavior is almost but not quite periodic. [2] The term used to denote oscillations that appear to follow a regular pattern but which do not have a fixed ...

  3. Reaction rate constant - Wikipedia

    en.wikipedia.org/wiki/Reaction_rate_constant

    where A and B are reactants C is a product a, b, and c are stoichiometric coefficients,. the reaction rate is often found to have the form: = [] [] Here ⁠ ⁠ is the reaction rate constant that depends on temperature, and [A] and [B] are the molar concentrations of substances A and B in moles per unit volume of solution, assuming the reaction is taking place throughout the volume of the ...

  4. Transition state theory - Wikipedia

    en.wikipedia.org/wiki/Transition_state_theory

    In 1884, Jacobus van 't Hoff proposed the Van 't Hoff equation describing the temperature dependence of the equilibrium constant for a reversible reaction: ⁡ = where ΔU is the change in internal energy, K is the equilibrium constant of the reaction, R is the universal gas constant, and T is thermodynamic temperature.

  5. Periodic trends - Wikipedia

    en.wikipedia.org/wiki/Periodic_trends

    In general, the atomic radius decreases as we move from left-to-right in a period, and it increases when we go down a group. This is because in periods, the valence electrons are in the same outermost shell. The atomic number increases within the same period while moving from left to right, which in turn increases the effective nuclear charge.

  6. Periodic function - Wikipedia

    en.wikipedia.org/wiki/Periodic_function

    A function with period P will repeat on intervals of length P, and these intervals are sometimes also referred to as periods of the function. Geometrically, a periodic function can be defined as a function whose graph exhibits translational symmetry , i.e. a function f is periodic with period P if the graph of f is invariant under translation ...

  7. Frequency - Wikipedia

    en.wikipedia.org/wiki/Frequency

    The period (symbol T) is the interval of time between events, so the period is the reciprocal of the frequency: T = 1/f. [ 2 ] Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals ( sound ), radio waves , and light .

  8. Period (periodic table) - Wikipedia

    en.wikipedia.org/wiki/Period_(periodic_table)

    Period 4 includes the biologically essential elements potassium and calcium, and is the first period in the d-block with the lighter transition metals. These include iron , the heaviest element forged in main-sequence stars and a principal component of the Earth, as well as other important metals such as cobalt , nickel , and copper .

  9. Acid dissociation constant - Wikipedia

    en.wikipedia.org/wiki/Acid_dissociation_constant

    These calculations find application in many different areas of chemistry, biology, medicine, and geology. For example, many compounds used for medication are weak acids or bases, and a knowledge of the p K a values, together with the octanol-water partition coefficient , can be used for estimating the extent to which the compound enters the ...