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Electronegativity is the measure of the ability of an atom within a covalent bond to attract the bonding pair of electrons [1]. Fluorine is the most electronegative element and the values decrease as you move left and down in the periodic table. To clarify this, the first few most electronegative elements are as the following: F, O, Cl, N, Br[2]. The electronegativity increases across the period C, N, O and F.

The difference in electronegativity between interacting atoms is important in determining the type of chemical bond between them [3]. The bond between a pair of identical atoms is purely Covalent, as both atoms have the same strength of attraction for the bonding electrons. In other words, there is no difference in Electronegativity values. However, when the atoms are different, even marginally, the bonding electrons are shared unequally and the bond has some Ionic character. The bonding electrons on the negative ion spend more time on the side facing the positive ion. They are always 'shared' to some small degree, as they spend more time in the space between the ions [4].


  1. http://www.chemguide.co.uk/atoms/bonding/electroneg.html
  2. http://www.rsc.org/periodic-table/trends
  3. http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/E/Electronegativity.html
  4. Senese, F. (2015). What is Electronegativity?. Available: http://antoine.frostburg.edu/chem/senese/101/bonds/faq/print-what-is-electronegativity.shtml. Last accessed 4th December 2015.
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