Electronegativity Scales

ELECTRONEGATIVITY SCALES Electronegativity surmount is an arbitary exceed. They ar based on various types of experimental data like hamper energy, dipole antenna antenna moment, ionisation potential and negatron affinity. Most ordinarily employ platefuls are 1. Paulings weighing machine 2. Mullikens scale 3. Sandersons scale 4. Alfred and Rochows scale Paulings scale (1932) This scale is based on an empirical relation b order of magnitude by the energy of a attach and the electronegativities of bonded atoms. Consider a bond A-B amongst two dissimilar atoms A and B of a molecule AB. allow the bond energies of A-A, B-B and A-B bonds be represented as EA-A, EB-B and EA-B respectively. It may be seen that the bond dissociation energy of A-B is nearly higher than the geometric mean of the bond dissociation energies of A-A and B-B bonds i.e., A B A A B B E E E ? ? ? > ? Their difference (?) is related to the difference in the electronegativities of A and B according to the by-line equation A B A A B B E E E ? ? ? ? ? ? 2 A B (X ?X ) (or) 0.208 ? = XA XB Here, XA and XB are the electronegativities of A and B respectively. The factor 0.208 arises from the conversion of Kcals to electron volt. Considering arbitarily the negativism of hydrogen to be 2.1, Pauling calculated electronegativities of other elements with the athletic supporter of this equation.

Disadvantage of Pauling scale The disadvantage of Paulings scale is that bond energies are not known with any storey of accuracy for many comforting elements. Problem Calculate the electronegativi ty of chlorine from the following data EH-H! = 104 K cal mol-1 ; ECl-Cl = 36 K cal mol-1 EH-Cl= 134 K cal mol-1 According to Paulings equation HCl H H Cl Cl _ E E ? E ? ? ? _ 134 ? 104?36 = 134 61.18 = 72.82 Cl H 0.208 _ X ?X X X 0.208 72.82 Cl H ? ? = 1.77 XCl - 2.1 = 1.77 [ XH = 2.1] XCl = 1.77 + 2.1 = 3.87 2. Mullikens master In 1934, Mulliken suggested an alternative attempt to electronegativity based on ionization energy...If you want to get a full essay, order it on our website: OrderCustomPaper.com

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