<P> Electronegativity, symbol χ, is a chemical property that describes the tendency of an atom to attract 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>

The ability of an atom to attract electron towards itself is called