﻿872 
  Dr. 
  N. 
  Bohr 
  on 
  the 
  Constitution 
  

  

  final 
  result 
  will 
  mainly 
  depend 
  on 
  the 
  number 
  of 
  electrons 
  in 
  

   these 
  rings. 
  If, 
  for 
  example, 
  the 
  outer 
  ring 
  in 
  both 
  atoms 
  

   contains 
  only 
  one 
  electron, 
  we 
  may 
  expect 
  that 
  during 
  the 
  

   approach 
  these 
  two 
  electrons 
  will 
  form 
  a 
  single 
  ring 
  as 
  in 
  the 
  

   case 
  of 
  hydrogen. 
  By 
  a 
  further 
  approach 
  of 
  the 
  nuclei, 
  the 
  

   system 
  will 
  arrive 
  at 
  a 
  state 
  of 
  equilibrium 
  before 
  the 
  distance 
  

   apart 
  of 
  the 
  nuclei 
  is 
  comparable 
  with 
  the 
  radii 
  of 
  the 
  inner 
  

   rings 
  of 
  electrons. 
  If 
  the 
  distance 
  be 
  decreased 
  still 
  further, 
  

   the 
  repulsion 
  of 
  the 
  nuclei 
  will 
  predominate 
  and 
  tend 
  to 
  

   prevent 
  an 
  approach 
  of 
  the 
  systems. 
  

  

  In 
  this 
  way 
  we 
  are 
  led 
  to 
  a 
  possible 
  configuration 
  of 
  a 
  

   molecule 
  of 
  a 
  combination 
  of 
  two 
  monovalent 
  substance? 
  — 
  

   such 
  as 
  HOI 
  — 
  in 
  which 
  the 
  ring 
  of 
  electrons 
  representing 
  

   the 
  chemical 
  bond 
  is 
  arranged 
  in 
  a 
  similar 
  way 
  to 
  that 
  

   assumed 
  for 
  a 
  hydrogen 
  molecule. 
  Since, 
  however, 
  as 
  in 
  

   the 
  case 
  of 
  hydrogen, 
  the 
  energy 
  emitted 
  by 
  a 
  combination 
  

   of 
  the 
  atoms 
  is 
  only 
  a 
  small 
  part 
  of 
  the 
  kinetic 
  energy 
  of 
  the 
  

   outer 
  electrons, 
  we 
  may 
  expect 
  that 
  small 
  differences 
  in 
  the 
  

   configuration 
  of 
  the 
  ring, 
  due 
  to 
  the 
  presence 
  of 
  inner 
  rings 
  

   of 
  electrons 
  in 
  the 
  atoms, 
  will 
  be 
  of 
  great 
  influence 
  on 
  the 
  

   heat 
  of 
  combination 
  and 
  consequently 
  on 
  the 
  affinity 
  of 
  the 
  

   substances. 
  As 
  mentioned 
  in 
  § 
  2, 
  a 
  detailed 
  discussion 
  of 
  

   these 
  questions 
  involves 
  elaborate 
  numerical 
  calculations. 
  

   AVe 
  may, 
  however, 
  make 
  an 
  approximate 
  comparison 
  of 
  the 
  

   theory 
  with 
  experiment, 
  by 
  considering 
  the 
  frequency 
  of 
  

   vibration 
  of 
  the 
  two 
  atoms 
  in 
  the 
  molecule 
  relative 
  to 
  each 
  

   other. 
  In 
  § 
  3, 
  p. 
  866, 
  we 
  have 
  calculated 
  this 
  frequency 
  for 
  a 
  

   hydrogen 
  molecule. 
  Since 
  now 
  the 
  binding 
  of 
  the 
  atoms 
  is 
  

   assumed 
  to 
  be 
  similar 
  to 
  that 
  in 
  hydrogen, 
  the 
  frequency 
  of 
  

   another 
  molecule 
  can 
  be 
  simply 
  calculated 
  if 
  we 
  know 
  the 
  

   ratio 
  of 
  the 
  mass 
  of 
  the 
  nuclei 
  to 
  be 
  that 
  of 
  a 
  hydrogen 
  

   nucleus. 
  Denoting 
  the 
  frequency 
  of 
  a 
  hydrogen 
  molecule 
  

   by 
  v 
  and 
  the 
  atomic 
  weights 
  of 
  the 
  substances 
  entering 
  in 
  

   the 
  combination 
  in 
  question 
  by 
  A 
  1 
  and 
  A 
  2 
  respectively, 
  we 
  

   get 
  for 
  the 
  frequency 
  

  

  * 
  = 
  "oV 
  

  

  M 
  + 
  A 
  2 
  

  

  2 
  a,a; 
  

  

  If 
  the 
  two 
  atoms 
  are 
  identical 
  the 
  molecule 
  will 
  be 
  exactly 
  

   symmetrical, 
  and 
  we 
  cannot 
  expect 
  an 
  absorption 
  of 
  radiation 
  

   corresponding 
  to 
  the 
  frequency 
  in 
  question 
  (comp. 
  p. 
  S66). 
  

   For 
  HC1 
  gas 
  an 
  infra-red 
  absorption 
  band 
  corresponding 
  to 
  a 
  

   frequency 
  of 
  about 
  8*5 
  . 
  10 
  13 
  is 
  observed*. 
  Putting 
  in 
  the 
  

   above 
  formula 
  A 
  x 
  = 
  l 
  and 
  A 
  2 
  = 
  35 
  and 
  using 
  the 
  value 
  for 
  v 
  

  

  * 
  See 
  II. 
  Kayser, 
  TIandb. 
  d. 
  Spectr. 
  iii. 
  p. 
  366 
  (1905). 
  

  

  