<P> Electronegativity, symbol χ, is a chemical property that describes the tendency of an atom to attract a shared pair of electrons (or electron density) towards itself . An atom's electronegativity is affected by both its atomic number and the distance at which its valence electrons reside from the charged nucleus . The higher the associated electronegativity number, the more an element or compound attracts electrons towards it . </P> <P> The term "electronegativity" was introduced by Jöns Jacob Berzelius in 1811, though the concept was known even before that and was studied by many chemists including Avogadro . In spite of its long history, an accurate scale of electronegativity was not developed until 1932, when Linus Pauling proposed an electronegativity scale, which depends on bond energies, as a development of valence bond theory . It has been shown to correlate with a number of other chemical properties . Electronegativity cannot be directly measured and must be calculated from other atomic or molecular properties . Several methods of calculation have been proposed, and although there may be small differences in the numerical values of the electronegativity, all methods show the same periodic trends between elements . </P> <P> The most commonly used method of calculation is that originally proposed by Linus Pauling . This gives a dimensionless quantity, commonly referred to as the Pauling scale (χ), on a relative scale running from around 0.7 to 3.98 (hydrogen = 2.20). When other methods of calculation are used, it is conventional (although not obligatory) to quote the results on a scale that covers the same range of numerical values: this is known as an electronegativity in Pauling units . </P>

Who is credited with deriving the electronegativity values of the periodic table