Electronegativity

Group electronegativity In organic chemistry, electronegativity is associated more with different functional groups than with individual atoms.

In general, the greater the difference in electronegativity between two atoms the more polar the bond that will be formed between them, with the atom having the higher electronegativity being at the negative end of the dipole.

The terms group electronegativity and substituent electronegativity are used synonymously.

This is particularly true of the transition elements, where quoted electronegativity values are usually, of necessity, averages over several different oxidation states and where trends in electronegativity are harder to see as a result.

Using electronegativity The use of electronegativity in this way was introduced by Linus Pauling in 1947.

Variation of electronegativity with oxidation number In inorganic chemistry it is common to consider a single value of the electronegativity to be valid for most "normal" situations.

A. L. Allred updated Pauling's original values in 1961 to take account of the greater availability of thermodynamic data, and it is these "revised Pauling" values of the electronegativity that are most often used.

A large difference in electronegativity leads to more polar (ionic) character in the bond.

An atom's electronegativity is affected by both its atomic number and the distance at which its valence electrons reside from the charged nucleus.

An atom's electronegativity is affected by both its atomic number and the distance between the valence electrons and the nucleus.

Because of the higher electronegativity of lithium, some of its compounds have a more covalent character.

Both these measurements depend on the s-electron density at the nucleus, and so are a good indication that the different measures of electronegativity really are describing "the ability of an atom in a molecule to attract electrons to itself".

Characteristics Properties A vial containing the black allotrope of antimony Native antimony with oxidation products Crystal structure common to Sb, AsSb and gray As Antimony is in the nitrogen group (group 15) and has an electronegativity of 2.05.

Chlorine has the highest electron affinity and the third highest electronegativity of all the reactive elements.

Covalent bonds are also affected by the electronegativity of the connected atoms which determines the chemical polarity of the bond.

Electronegativity increases in the same manner as ionization energy because of the pull exerted on the electrons by the nucleus.

Gold has the highest Pauling electronegativity of any metal, with a value of 2.54, making the auride anion relatively stable.

Huheey, Keiter & Keiter, pp. 42, 880–81 Metallic character The lower the values of ionization energy, electronegativity and electron affinity, the more metallic character the element has.

Hydrogen was chosen as the reference, as it forms covalent bonds with a large variety of elements: its electronegativity was fixed first at 2.1, later revised citation to 2.20.

In 1947 Linus Pauling proposed that the oxidation number could be determined using the electronegativity of the atoms to determine the "ions" in the formal determination of oxidation number.