Neutral atom electronegativity

Negative oxidation state. 580-581 Neon. 163-164 Nephelauxetic effect. 413 Neutral atom electronegativity. 186... 

The standard bond lengths from Sutton, L.E. Tables of Interatomic Distances and ConAguration in Molecules and Ions, The Chemical Society, London 1958, were assumed, together with the experimental neutral atom electronegativity and hardness parameters [11]... 

When describing the ground-states of neutral molecules, it is desirable that the formal charges be small in magnitude, i.e. less than imity. This requirement should be particularly appropriate when atoms A and B have fairly similar neutral atom electronegativities. 

Hydrogen bonds are due to the attractive forces between the distorted electron cloud of a hydrogen atom and other more electronegative atoms such as oxygen and nitrogen. The attractive forces are weaker than covalent bonds, but many hydrogen bonds can be formed in macromolecular protein molecules. Van der Waals forces are weaker attractive forces, due to the attraction between neutral atoms. 

Electronegativity is the ability (in terms of structure and energy level of electrons) of either neutral atoms or molecules to attract bonding electrons to them. In essence, electronegativity is a measurement of how effectively an atom within a molecule is able to attract bonding electrons to itself. 

This was justified as follows. The energy required to take an electron from a neutral atom Y to a neutral atom Z is /Y — AZt whereas the energy cost to take an electron from a neutral atom Z to a neutral atom Y is Iz — Ay. Hence, the two atoms Y and Z would have an equal propensity for attracting electrons or equal electronegativity if /Y — Az = Iz — AY, that is if IY + Ay = Iz + Az. This is consistent with the Mulliken definition, eqn (3.35), the factor 1/2 being arbitrary. As can be seen by comparing the two different scales in Fig. 3.5, the Mulliken values are approximately 2.8 times the Pauling values. 

Equalization of atomic electronegativities implies that their magnitudes must be able to vary as the atoms interact. One way to formulate this is to first express the energy E of an atom in a molecule as a function of the number of electrons N that are associated with it in the molecule, and then to expand E(N) in a Taylor s series around N0, the number of electrons in the neutral atom13-15 (equation 2). 

The second and succeeding terms on the right side of equation 4 give the amount by which the electronegativity of the neutral atom, % (N0), is changed by the gain or loss of electrons... 

E(Z, N) — E(Z, N— 1), that is from an ionization potential. Indeed it has already been seen in Section 7 that, for a neutral atom, n is in magnitude approximately half the ionization potential, for the case when the electron affinity is sufficiently small to be neglected. Mulliken s definition of electronegativity, namely... 

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