﻿870 
  Dr. 
  N. 
  Bohr 
  on 
  the 
  Constitution 
  

  

  of 
  the 
  nuclei 
  as 
  in 
  the 
  combination 
  of 
  two 
  neutral 
  atoms. 
  

   For 
  a 
  certain 
  distance 
  apart 
  of 
  the 
  nuclei 
  the 
  configuration 
  

   of 
  the 
  electrons 
  will 
  be 
  unstable 
  and 
  suddenly 
  change 
  by 
  a 
  

   finite 
  amount 
  ; 
  this 
  is 
  immediately 
  deduced 
  from 
  the 
  fact 
  

   that 
  the 
  motion 
  of 
  the 
  electrons 
  by 
  the 
  combination 
  of 
  two 
  

   neutral 
  hydrogen 
  atoms 
  considered 
  above, 
  passes 
  through 
  an 
  

   uninterrupted 
  series 
  of 
  stable 
  configurations. 
  The 
  work 
  

   done 
  by 
  the 
  system 
  against 
  the 
  extraneous 
  forces 
  acting 
  on 
  

   the 
  nuclei 
  will 
  therefore, 
  in 
  the 
  case 
  of 
  the 
  combination 
  of 
  a 
  

   negatively 
  and 
  a 
  positively 
  charged 
  atom, 
  not 
  be 
  equal 
  to 
  the 
  

   difference 
  in 
  energy 
  between 
  the 
  original 
  ami 
  the 
  final 
  con- 
  

   figuration 
  ; 
  but 
  in 
  passing 
  through 
  the 
  unstable 
  configurations 
  

   a 
  radiation 
  of 
  energy 
  must 
  be 
  emitted, 
  corresponding 
  to 
  that 
  

   emitted 
  during 
  the 
  binding 
  of 
  electrons 
  by 
  a 
  single 
  nucleus 
  

   and 
  considered 
  in 
  Parts 
  I. 
  and 
  II. 
  

  

  On 
  the 
  above 
  view, 
  it 
  follows 
  that 
  in 
  the 
  breaking 
  up 
  of 
  a 
  

   hydrogen 
  molecule 
  by 
  slowly 
  increasing 
  the 
  distance 
  apart 
  

   of 
  the 
  nuclei, 
  we 
  obtain 
  two 
  neutral 
  hydrogen 
  atoms 
  and 
  not 
  

   a 
  positively 
  and 
  a 
  negatively 
  charged 
  one. 
  This 
  is 
  in 
  agree- 
  

   ment 
  with 
  deductions 
  drawn 
  from 
  experiments 
  on 
  positive 
  

   rays 
  *. 
  

  

  Next 
  imagine 
  that 
  instead 
  of 
  two 
  hydrogen 
  atoms 
  we 
  con- 
  

   sider 
  two 
  helium 
  atoms, 
  i. 
  e. 
  systems 
  consisting 
  of 
  a 
  nucleus 
  

   of 
  charge 
  2e 
  surrounded 
  by 
  a 
  ring 
  of 
  two 
  electrons, 
  and 
  go 
  

   through 
  a 
  similar 
  process 
  to 
  that 
  considered 
  on 
  p. 
  868. 
  

   Assume 
  that 
  the 
  helium 
  atoms 
  at 
  the 
  beginning 
  of 
  the 
  

   operation 
  are 
  orientated 
  relatively 
  to 
  each 
  other 
  like 
  the 
  

   hydrogen 
  atoms, 
  but 
  with 
  the 
  exception 
  that 
  the 
  phases 
  of 
  

   the 
  electrons 
  in 
  the 
  helium 
  atoms 
  differ 
  by 
  one 
  quarter 
  of 
  a 
  

   revolution 
  instead 
  of 
  one 
  half 
  revolution 
  as 
  in 
  the 
  case 
  of 
  

   hydrogen. 
  By 
  the 
  displacement 
  of 
  the 
  nuclei, 
  the 
  planes 
  of 
  

   the 
  rings 
  of 
  electrons 
  will, 
  as 
  in 
  the 
  former 
  case, 
  approach 
  

   each 
  other 
  at 
  a 
  higher 
  rate 
  than 
  the 
  nuclei, 
  and 
  for 
  a 
  certain 
  

   position 
  of 
  the 
  latter 
  the 
  planes 
  will 
  coincide. 
  During 
  the 
  

   further 
  approach 
  of 
  the 
  nuclei, 
  the 
  electrons 
  will 
  be 
  arranged 
  

   at 
  equal 
  angular 
  intervals 
  in 
  a 
  single 
  ring. 
  As 
  in 
  the 
  former 
  

   case, 
  it 
  can 
  be 
  shown 
  that 
  at 
  any 
  moment 
  during 
  this 
  operation 
  

   the 
  system 
  will 
  be 
  stable 
  for 
  a 
  displacement 
  of 
  the 
  electrons 
  

   perpendicular 
  to 
  the 
  plane 
  of 
  the 
  rings. 
  Contrary, 
  however, 
  

   to 
  what 
  took 
  place 
  in 
  the 
  case 
  of 
  hydrogen, 
  the 
  extraneous 
  

   forces 
  to 
  be 
  applied 
  to 
  the 
  nuclei 
  in 
  order 
  to 
  keep 
  the 
  system 
  

   in 
  equilibrium 
  will 
  always 
  be 
  in 
  a 
  direction 
  to 
  diminish 
  the 
  

   distance 
  apart 
  of 
  the 
  nuclei, 
  and 
  the 
  system 
  will 
  never 
  pass 
  

   through 
  a 
  configuration 
  of 
  equilibrium 
  ; 
  the 
  helium 
  atoms 
  

  

  * 
  Comp. 
  J. 
  J. 
  Thomson. 
  Phil. 
  May. 
  xxiv. 
  p. 
  248 
  (1912). 
  

  

  