Electronegativity is a measure of the tendency of a bonded atom to attract electrons to itself.
Atoms of higher electronegativity have a greater attraction for the electrons at that atom, both the electrons in bonds at that atom and its non-bonding electron pairs.
The first step in understanding and using electronegativity is realising that the positions of the elements in the periodic table can be used to predict which of a bonded pair of atoms is more electronegative.
Atoms of higher electronegativity have a greater attraction for the electrons at that atom, both the electrons in bonds at that atom and its non-bonding electron pairs.
| Pauling Electronegativity** |  | H 2.2 |  | He | ||||
| Li 1.0 | Be 1.6 | B 2.0 | C 2.6 | N 3.0 | O 3.4 | F 4.0 | Ne | |
| Na 0.93 | Mg 1.3 | Al 1.6 | Si 1.9 | P 2.2 | S 2.6 | Cl 3.2 | Ar | |
| K 0.82 | Ca 1.0 | Ga 1.6 | Ge 1.8 | As 2.2 | Se 2.6 | Br 3.0 | Kr | |
| Rb 0.82 | Sr 0.95 | In 1.8 | Sn 2.0 | Sb 2.1 | Te 2.1 | I 2.7 | Xe | |
| Cs 0.79 | Ba 0.89 | Tl 1.6 | Pb 1.9 | Bi 2.0 | Po 2.0 | At | ||
| **This is an internationally-accepted scale. | ||||||||
The first step in understanding and using electronegativity is realising that the positions of the elements in the periodic table can be used to predict which of a bonded pair of atoms is more electronegative.
The electronegativity is higher for elements that are
more to the right in a period
closer to top of a group in the periodic table.
Thus non-metals are more electronegative than metals.
more to the right in a period
closer to top of a group in the periodic table.
Thus non-metals are more electronegative than metals.
Thus relative electronegativities can be used to predict electron distribution in a compound.
Knowledge of the more positive and more negative regions of the compound can be used to understand
The more electronegative atom in a bond has a larger share of the electrons and is more negative.
The less electronegative atom in a bond has a lesser share of the electrons is more positive.
Why is understanding of electron distribution important? The less electronegative atom in a bond has a lesser share of the electrons is more positive.
The charge density (electrostatic potential) maps of H2O and Cl2 have been generated in a molecular modeling program which shows more positive atoms in a bond as blue and more negative atoms as red. This shows oxygen (the more electronegative element) is more negative than hydrogen. It also shows that electrons are shared equally if the atoms are the same.
 H2O |  Cl2 |
Knowledge of the more positive and more negative regions of the compound can be used to understand
the type of bonding between atoms in the compound
the reactivity of the compound.
the reactivity of the compound.