Electronegativity
Overview
Electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons (or electron density) towards itself. This concept was introduced by the American chemist Linus Carl Pauling and has been a fundamental principle in the study of chemistry, particularly in understanding the nature of bonds between atoms in a molecule.
Definition and Measurement
Electronegativity is measured on several scales, the most commonly used being the Pauling scale, named after its developer. On this scale, the most electronegative element (fluorine) is assigned a value of 4.0, and values range down to cesium and francium which are the least electronegative at 0.7.
Factors Influencing Electronegativity
Several factors influence the electronegativity of an atom. These include the atom's atomic number, the distance between the atom's nucleus and its valence electrons (atomic radius), and the number of places in its outer electron shell that are occupied by electrons.
Electronegativity and Chemical Bonding
Electronegativity plays a crucial role in determining the type of bond that forms between two atoms. If the electronegativity difference between the atoms is large, an ionic bond forms. If the difference is small, a covalent bond forms. If there is no difference (as in diatomic molecules), a pure covalent bond forms.
Trends in the Periodic Table
In the periodic table, electronegativity tends to increase from left to right across a period (due to increasing nuclear charge) and decrease down a group (due to increasing atomic radius).
Applications of Electronegativity
Electronegativity is a fundamental concept in chemistry and is used in a wide range of applications, from predicting the nature of chemical reactions to designing new materials.
See Also
Chemical bond Ionic bond Covalent bond Periodic table Chemical reaction