![]() ![]() ![]() Electron affinities are defined at absolute zero while electron gain enthalpies at 298 K.Electron affinity and electron gain enthalpy have same magnitude but opposite sign.Electron affinity is defined as absolute zero and, therefore at any other temperature (T) heat capacities of the reactants and the products have to be taken into account in.If energy has to be supplied to add an electron to an atom, then the electron affinity of the atom is assigned a negative sign.If energy is released when an electron is added to an atom, the electron affinity is taken as positive.The negative of the enthalpy change is defined as the electron affinity (A e) of the atom under consideration.Therefore, the order of Δ e g H is s > p > d > f. Magnitude of Δ e g H ∝ penetrating power.For group 18 elements i.e., noble gases, energy is required to add an electron as it has to enter the next higher principal quantum level leading to a very unstable electronic configuration.įactors Affecting Electron Gain Enthalpy:.Example: For group 17 elements i.e., halogens Δ eg H is negative as they can gain an electron and attain the stable noble gas configuration.The process of adding an electron to the atom can be either endothermic or exothermic.Electron gain enthalpy provides a measure of the ease with which an atom adds an electron to form anion.The energy change involved when an extra electron is added to an isolated gaseous atom is called the electron gain enthalpy Δ eg.The reducing power increases on going down a group because the IP value decreases. IE ∝ 1/ metallic or electropositive character.The IE of the metalloids generally falls between those of metals and non-meta.He has the highest and Cshas the lowest ionization energy.Alkali metals have the lowest and inert gases have the highest IE in a period. ![]() This is because of the stable configuration, i.e., (n−1) d 10 ns 2of these elements. The first ionization enthalpy of elements of group 12 (IIB) is higher than their immediate neighbors.The s-subshell is nearest to the nucleus while f-subshell is farthest from the nucleus These are denoted as I 1, I 2, I 3,…, for 1st electron, 2nd electron, 3rd electron and so on respectively. An atom can have as many ionization energies as number of electrons it has.Units: kJ / mol (for ionization potential, units: eV/atom.).(If given in terms of the amount of work done in removing an electron, the property is called ionization potential.) It is the amount of energy required to remove an electron from the outermost orbit of an isolated gaseous atom. ![]()
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