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Electronegativity

Electronegativity. Definition. The property which describes the ability of an atom in a molecule to attract electrons to itself in a covalent bond. The values may differ depending on methods used in calculation. Represented by the symbol χ

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Electronegativity

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  1. Electronegativity

  2. Definition • The property which describes the ability of an atom in a molecule to attract electrons to itself in a covalent bond. • The values may differ depending on methods used in calculation. • Represented by the symbolχ • Since it is not a measured value, there is no units for electronegativity.

  3. Trend (Column) • As you go down the column the magnitude of electronegativity decreases. • This is due to shielding • As you get down the periodic table, the number of electron shells increases.

  4. Trend (Row) • As you go across the row, the magnitude of electronegativity increases. • Electronegativity is heavily related with the ionization energy; as ionization energy increases across the row, electronegativity is also increases. • Although the number of electrons is increasing, shielding is negligible for group1-18 because each extra electron enters the same electron subshell.

  5. Exception • Lanthanides and actinides: the composition of these elements are different from those elements that follows the trend. Hydrogen • Transition metals: They also have different • Noble gases: these elements possess full electron shells. Therefore they do not attract the electrons and their electronegativity values are almost zero. • However, since it is calculation, there ARE defined electronegativity values for noble gasses.

  6. Different Scales of Electronegativity • There are several scientists came up with methods to define χ. • Pauling: first proposed the concept of electronegativity using dissociation enegies • Mulliken: used arithmetic mean of the first ionization energy to defineχ • Allred-Rochow: used Z* values to calculate the electronegativity • Sanderson:Came up with a calculation using reciprocal of the atomic volume • Although they are different scales, all electronegativity behave in similar way.

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