Electronegativity The tendency of an atom in a molecule to attract shared electrons

Electronegativity the tendency of an atom in a molecule to attract shared electrons to itself. (13.2)... 

As has just been described, when a covalent bond forms between two atoms, there is no reason to assume that the pair of electrons is shared equally between the atoms. What is needed is some sort of way to provide a relative index of the ability of an atom to attract electrons. Linus Pauling developed an approach to this problem by describing a property now known as the electronegativity of an atom. This property gives a measure of the tendency of an atom in a molecule to attract electrons. Pauling devised a way to give numerical values to describe this property that makes use of the fact that the covalent bonds between atoms of different electronegativity are more stable than if they were purely... 

When two atoms form a covalent bond, they do not share the electrons equally unless the atoms are identical. The concept of electronegativity was introduced by Linus Pauling to explain the tendency of an atom in a molecule to attract electrons. The basis for Pauling s... 

Covalent bonds may be either polar or nonpolar. In a nonpolar bond such as that in the hydrogen molecule, H2, (H H or H—H) the electron pair is shared equally between the two hydrogen nuclei. We defined electronegativity as the tendency of an atom to attract electrons to itself in a chemical bond (see Section 6-6). Both H atoms have the same electronegativity. This means that the shared electrons are equally attracted to both hydrogen nuclei and therefore spend equal amounts of time near each nucleus. In this nonpolar covalent bond, the electron density is s)mimetrical about a plane that is perpendicular to a line between the two nuclei. This is true for all homonuclear diatomic molecules, such as H2, O2, N2, F2, and CI2, because the two identical atoms have identical electronegativities. We can generalize ... 

The separation of charge in a polar covalent bond creates an electric dipole. We expect the dipoles in the covalent molecules HF, HCl, HBr, and HI to be different because F, Cl, Br, and I have different electronegativities. This tells us that atoms of these elements have different tendencies to attract an electron pair that they share with hydrogen. We indicate this difference as shown here, where A(EN) is the difference in electronegativity between two atoms that are bonded together. 

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