Electronegativity Scales

ELECTRONEGATIVITY SCALES Electronegativity surmount is an arbitary surmount. They ar based on various types of experimental data like hamper energy, dipole antenna antenna moment, ionisation potential and electron affinity. Most unremarkably employ home plates are 1. Paulings scale 2. Mullikens scale 3. Sandersons scale 4. Alfred and Rochows scale Paulings scale (1932) This scale is based on an empirical relation ring 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 roughly 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 b y-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 negativeness of hydrogen to be 2.1, Pauling calculated electronegativities of other elements with the gymnastic supporter of this equation.

Disadvantage of Pauling scale The disadvantage of Paulings scale is that bond energies are not known with any class of accuracy for many comforting elements. Problem Calculate the electronegativity 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 equ! ation 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 home In 1934, Mulliken suggested an alternative attempt to electronegativity based on ionization energy...If you want to get a full essay, regularise it on our website: OrderEssay.net

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