﻿of 
  Atoms 
  and 
  Molecules. 
  869 
  

  

  saying 
  that 
  the 
  atoms 
  have 
  " 
  attracted 
  " 
  each 
  other 
  during 
  

   the 
  combination. 
  A 
  closer 
  calculation 
  shows 
  that 
  For 
  any 
  

   distance 
  apart 
  o£ 
  the 
  nuclei 
  greater 
  than 
  that 
  corresponding 
  

   to 
  the 
  configuration 
  of 
  equilibrium, 
  the 
  forces 
  acting 
  on 
  the 
  

   nuclei, 
  due 
  to 
  the 
  particles 
  of 
  the 
  system, 
  will 
  be 
  in 
  such 
  a 
  

   direction 
  as 
  to 
  diminish 
  the 
  distance 
  between 
  the 
  nuclei 
  ; 
  

   while 
  for 
  any 
  smaller 
  distance 
  the 
  forces 
  will 
  have 
  the 
  

   opposite 
  direction. 
  

  

  By 
  means 
  of 
  these 
  considerations, 
  a 
  possible 
  process 
  is 
  

   indicated 
  for 
  the 
  combination 
  of 
  two 
  hydrogen 
  atoms 
  to 
  

   form 
  a 
  molecule. 
  This 
  operation 
  can 
  be 
  followed 
  step 
  by 
  

   step 
  without 
  introducing 
  any 
  new 
  assumption 
  on 
  the 
  

   dynamics 
  of 
  the 
  electrons, 
  and 
  leads 
  to 
  the 
  same 
  con- 
  

   figuration 
  adopted 
  in 
  § 
  3 
  for 
  a 
  hydrogen 
  molecule. 
  It 
  may 
  

   be 
  recalled 
  that 
  the 
  latter 
  configuration 
  was 
  deduced 
  directly 
  

   by 
  help 
  of 
  the 
  principal 
  hypothesis 
  of 
  the 
  universal 
  constancy 
  

   of 
  the 
  angular 
  momentum 
  of 
  the 
  electrons. 
  These 
  con- 
  

   siderations 
  also 
  offer 
  an 
  explanation 
  of 
  the 
  " 
  affinity 
  " 
  of 
  two 
  

   atoms. 
  It 
  may 
  be 
  remarked 
  that 
  the 
  assumption 
  in 
  regard 
  

   to 
  the 
  slowness 
  of 
  the 
  motion 
  of 
  the 
  nuclei 
  relative 
  to 
  those 
  

   of 
  the 
  electrons 
  is 
  satisfied 
  to 
  a 
  high 
  degree 
  of 
  approximation 
  

   in 
  a 
  collision 
  between 
  two 
  atoms 
  of 
  a 
  gas 
  at 
  ordinary 
  tem- 
  

   peratures. 
  In 
  assuming 
  a 
  special 
  arrangement 
  of 
  the 
  

   electrons 
  at 
  the 
  beginning 
  of 
  the 
  process, 
  very 
  little 
  infor- 
  

   mation, 
  however, 
  is 
  obtained 
  by 
  this 
  method 
  on 
  the 
  chance 
  

   of 
  combination 
  due 
  to 
  an 
  arbitrary 
  collision 
  between 
  two 
  

   atoms. 
  

  

  Another 
  way 
  in 
  which 
  a 
  neutral 
  hydrogen 
  molecule 
  may 
  be 
  

   formed 
  is 
  by 
  the 
  combination 
  of 
  a 
  positively 
  and 
  a 
  negatively 
  

   charged 
  atom. 
  According 
  to 
  the 
  theory 
  a 
  positively 
  charged 
  

   hydrogen 
  atom 
  is 
  simply 
  a 
  nucleus 
  of 
  vanishing 
  dimensions 
  

   and 
  of 
  charge 
  <?, 
  while 
  a 
  negatively 
  charged 
  atom 
  is 
  a 
  system 
  

   consisting 
  of 
  a 
  nucleus 
  surrounded 
  by 
  a 
  ring 
  of 
  two 
  electrons. 
  

   As 
  shown 
  in 
  Part 
  II., 
  the 
  latter 
  system 
  may 
  be 
  considered 
  

   as 
  possible, 
  since 
  the 
  energy 
  emitted 
  by 
  the 
  formation 
  of 
  it 
  

   is 
  greater 
  than 
  the 
  corresponding 
  energy 
  for 
  a 
  neutral 
  

   hydrogen 
  atom. 
  Let 
  us 
  now 
  imagine 
  that, 
  by 
  a 
  slow 
  dis- 
  

   placement 
  of 
  the 
  nuclei, 
  as 
  before, 
  a 
  negatively 
  and 
  a 
  

   positively 
  charged 
  atom 
  combine. 
  We 
  must 
  assume 
  that, 
  

   when 
  the 
  nuclei 
  have 
  approached 
  a 
  distance 
  equal 
  to 
  that 
  in 
  

   the 
  configuration 
  adopted 
  for 
  a 
  hydrogen 
  molecule, 
  the 
  

   electrons 
  will 
  be 
  arranged 
  in 
  the 
  same 
  way, 
  since 
  this 
  is 
  the 
  

   only 
  stable 
  configuration 
  for 
  this 
  distance 
  in 
  which 
  the 
  

   angular 
  momentum 
  of 
  the 
  electrons 
  has 
  the 
  value 
  prescribed 
  

   by 
  the 
  theory. 
  The 
  state 
  of 
  motion 
  of 
  the 
  electrons 
  will, 
  

   however, 
  not 
  vary 
  in 
  a 
  continuous 
  way 
  with 
  the 
  displacement 
  

  

  