electronegativity


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electronegativity

(ĭlĕk'trōnĕgətĭv`ətē), in chemistry, tendency for an atom to attract a pair of electrons that it shares with another atom (see chemical bondchemical bond,
mechanism whereby atoms combine to form molecules. There is a chemical bond between two atoms or groups of atoms when the forces acting between them are strong enough to lead to the formation of an aggregate with sufficient stability to be regarded as an
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). For example, the molecule hydrogen chloride, HCl, consists of a hydrogen atom, H, and a chlorine atom, Cl, sharing a pair of electrons. If the pair of electrons are not shared equally, i.e., if they spend more time with one atom than with the other, the favored atom is said to be more electronegative. In the case of HCl, measurements indicate that the molecule has a dipole moment, that is, the chlorine end is relatively negative and the hydrogen end is relatively positive. This means that the electron pair spends more time with the chlorine atom than with the hydrogen atom and thus chlorine is more electronegative than hydrogen. Nonmetals have much higher electronegativities than metals; of the nonmetals, fluorine is the most electronegative, followed by oxygen, nitrogen, and chlorine. The larger the difference in electronegativity between two atoms, the more polar the bond between them. In the extreme case of a bond between a metal and a nonmetal, a complete transfer of electrons takes place.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Electronegativity

 

a quantity that characterizes the power of an atom in a molecule to attract electrons that take part in the formation of chemical bonds. Several methods have been developed for the calculation of electronegativity. For example, in 1935, R. Mulliken suggested that the sum of an atom’s ionization potential and electron affinity could serve as a measure of the atom’s electronegativity. In 1932, L. Pauling proposed another, more complicated method (seeCHEMICAL BOND). However, all the known methods turn out to yield virtually identical results.

If electronegativities are known, the electron density distribution in the molecules of many chemical substances may be approximately estimated. For example, the polarity of a covalent bond can be determined.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Pearson, Absolute hardness: companion parameter to absolute electronegativity, J.
where ([[chi].sub.M], [[eta].sub.M]) and ([[chi].sub.inh], [[eta].sub.inh]) are, respectively, the electronegativity and hardness of the metal and the inhibitor when [[phi].sub.M] is the work function.
[3] Fluorine's electronegativity creates a strong interaction with calcium.
The fluorine atom has the highest electronegativity of all the atoms and thus the C-F bond has a high polarity.
The electronegativity of the fluorine atom in flouroelastomers implies strong and very short distance C-F bonds, higher strength of C-C bonds, and also very strong Van Der Waals forces between hydrogen and fluorine atoms (refs.
The compound sodium fluoride has an electronegativity of three due to the combination of fluorine's electronegativity of four forming an ionic bond with sodium's electronegativity of one.
Based on the above size and electronegativity considerations, it should be possible to encapsulate Li atom in [C.sub.28] cage.
The slightly acidic properties of the boronic acid functional groups, combined with the electronegativity tendency from its nitrogen atom, may contribute to the inhibition activity to the [Zn.sup.2+] metalloenzyme pocket [62].
Moreover, the copolymer diblock has several oxygen ether groups of high electronegativity in its methyl/ethyl methacrylate moieties which could lead to an ion-dipole attraction between oppositely charged of these groups with Lys and Arg residues on the Mb surface.
This diversity is depending strongly on the site occupied by [Pb.sup.2+] ions, electronegativity of the ligand, crystal structure of the host lattice, and temperature [14, 37].