﻿848 Mr. J. H. Van Vleck on the normal Helium Atom 



hydrogen atom and the diatomic molecules of band spectrum 

 theory it is the total angular momentum of the entire system 

 (comprising two bodies), rather than the maximum angular 

 momentum of a single electron, which must be equal to 



■ — . Also one would expect Langmuir's now quantum 



27T 



condition to be equally applicable to his semicircular model 

 of the hydrogen molecule, for the latter is almost identical 

 with his semicircular helium atom, as the two electrons 

 oscillate back and forth about the centre of the line joining 

 the two hydrogen nuclei. However, computations made by 

 the writer indicate that the maximum angular momentum of 



a single electron must be '955 ^— , instead of exactly — , if the 



ionization potential of hydrogen is to have the proper value, 

 so that the scheme which works so well in helium does not 

 seem to yield correct results for a similar case in hydrogen. 



Langmuir's other suggestion consists essentially in 

 replacing the centrifugal force term found in the ordinary 

 dynamical Bohr theory of the hydrogen atom by a statical 

 force .of equal magnitude, leading to a static atom. This 

 force may be accounted for by assuming that the electron is 



1 fnh\ 2 

 an electrical doublet of strength ^ — ( 77- | . The super- 



6 2em \2ir) r 



position of this new static force on the ordinary Coulomb 

 force appears contradictory to the scattering experiments 

 of Rutherford on the validity of the inverse square law, 

 and to the dynamical orbits found in band spectrum and 

 specific heat theory. This static theory yields the correct 

 ionization potentials for the helium atom and the hydrogen 

 molecule *, but the strength of the electrical doublet 

 would have to be modified to depend on the mass of 

 the attracting nucleus, which is highly improbable, in order 

 to explain the observed shift between the lines of the Balmer 

 series of hydrogen and those of the Pickering series of 

 helium, a shift which the ordinary dynamical theory 

 naturally accounts for as a correction for the motion of the 

 nucleus. A further objection to the electrical doublet 

 interpretation of the new static force is that the doublet 

 would presumably orient itself so as to be attracted rather 

 than repelled by the nucleus, giving a force of wrong sign 

 (centripetal rather than centrifugal). Other difficulties 

 confronting any static atom are explanation of the Stark and 

 * Bulletin of the National Research Council, no. 14, p. 347. 



