CHM 124 Lecture Notes - Lecture 8: Pi Bond, Bromine, Nucleophilic Substitution
Document Summary
This page deals with electronegativity in an organic chemistry context. If you want a wider view of electronegativity, there is a link at the bottom of the page. Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The pauling scale is the most commonly used. Fluorine (the most electronegative element) is given a value of 4. 0, and values range down to caesium and francium which are the least electronegative at 0. 7. The most obvious example of this is the bond between two carbon atoms. Both atoms will attract the bonding pair to exactly the same extent. That means that on average the electron pair will be found half way between the two nuclei, and you could draw a picture of the bond like this: It is important to realise that this is an average picture. The electrons are actually in a sigma orbital, and are moving constantly within that orbital.