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The standard state of a material (pure substance, mixture or solution) is a reference point used to calculate its properties under different conditions.A degree sign (°) or a superscript Plimsoll symbol (⦵) is used to designate a thermodynamic quantity in the standard state, such as change in enthalpy (ΔH°), change in entropy (ΔS°), or change in Gibbs free energy (ΔG°).
Ionization energy is positive for neutral atoms, meaning that the ionization is an endothermic process. Roughly speaking, the closer the outermost electrons are to the nucleus of the atom, the higher the atom's ionization energy. In physics, ionization energy (IE) is usually expressed in electronvolts (eV) or joules (J).
Enthalpy (/ ˈ ɛ n θ əl p i / ⓘ) is the sum of a thermodynamic system's internal energy and the product of its pressure and volume. [1] It is a state function in thermodynamics used in many measurements in chemical, biological, and physical systems at a constant external pressure, which is conveniently provided by the large ambient atmosphere.
The ionization energy is the minimum amount of energy that an electron in a gaseous atom or ion has to absorb to come out of the influence of the attracting force of the nucleus. It is also referred to as ionization potential. The first ionization energy is the amount of energy that is required to remove the first electron from a neutral atom.
The first of these quantities is used in atomic physics, the second in chemistry, but both refer to the same basic property of the element. To convert from "value of ionization energy" to the corresponding "value of molar ionization energy", the conversion is: 1 eV = 96.48534 kJ/mol 1 kJ/mol = 0.0103642688 eV [12]
The enthalpy, entropy and Gibbs energy of activation are more correctly written as Δ ‡ H o, Δ ‡ S o and Δ ‡ G o respectively, where the o indicates a quantity evaluated between standard states. [11] [12] However, some authors omit the o in order to simplify the notation. [13] [14]
This differs by sign from the energy change of electron capture ionization. [1] The electron affinity is positive when energy is released on electron capture. In solid state physics , the electron affinity for a surface is defined somewhat differently ( see below ).
The terms fractional ionization and ionization fraction are also used to describe either the proportion of neutral particles that are ionized or the proportion of free electrons. [ 3 ] [ 4 ] When referred to an atom, "fully ionized" means that there are no bound electrons left, resulting in a bare nucleus .