The Negative Hydrogen Ion

Chandrasekhar, S., Astrophys. J. 100, 176, "Some remarks on the negative hydrogen ion and its absorption coefficient."... 

One of the most important rules about resonance is that resonance can occur only among structures with the same number of unpaired electrons. Since the electrons in the negative hydrogen ion, occupying the same orbital, are paired and the electrons involved in a bond formed by structures I and II are paired, this condition is satisfied, and we expect structures III and IV as well as I and II to be of significance for the normal hydrogen molecule. 

As an example, for the negative hydrogen ion the calculated value is —0.527463 compared to the experimental value of —0.527731, but the absolute value of the round-off error is 0.0005 based on calculating some of the integrals in reverse order. 

By internal consistency, I mean that a correction applied to one instance, say the negative hydrogen ion, applies to all instances of the same group, in this case, He-I through O-VI, but also, the theory is developed in general, with no special instances where any constants must be adjusted individually, or ad hoc additions are necessary. 

Experimental energies are adapted from Moore (1971), with the exception of the negative hydrogen ion, which are adapted from Kinghom and Adamowicz (1997). Other data are from Lide (1999), and Herzberg (1989). 

Included in the table is the value 0.7149 v.e. for the ionization energy of the negative hydrogen ion H. This shows that the hydrogen atom has a positive electron affinity, amounting to 16480 cal/mole. The consideration of the crystal energy of the alkali hydrides has provided a rough verification of this value. 

The negative hydrogen ion (H ), or hydrogen with an extra electron attached, is a glaring example of the necessity of quantum mechanical theory to describe atomic behavior. Classical physics, considering only electrostatic forces among the three charged particles, predicts that this ion should not exist in a stable, bound state. Yet H has been observed experimentally for decades. 

S. Chandrasekhar, Astrophys. J., 100,176 (1944). Some Remarks on the Negative Hydrogen Ion and Its Absorption Coefficient. 

Remember that an acid-base reaction is a double displacement reaction. Therefore, if sulfuric acid and potassium hydroxide are mixed, the positive ions trade places. The hydrogen ions from the sulfuric acid will react with the negative hydroxide ions to form water. Because a hydrogen ion has a charge of + 1 and a hydroxide ion has a charge of -1, they bond in a 1 1 ratio ... 

The behaviour of acids derived from the lower oxides of phosphorus is of particular interest. It has been seen that H3P02 behaves exclusively as a monobasic acid, and H3P03 as a dibasic one, from which it can be deduced that in the latter, as well as in the former, hydrogen ions are directly bound to the phosphorus. If an ionic formula is set up for these acids, taking this fact into account, then part of the hydrogen must be shown as negative, and the following... 

The values of the free energy of formation of the negative halogenide ions (plus hydrogen ion) in aqueous solution might be expected to depend in a simple way on the electronegativity of the atoms. It is found (Fig. XI-1) that there is a linear relation, represented by the equation... 

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