﻿486 
  Dr. 
  N. 
  Bohr 
  on 
  the 
  Constitution 
  

  

  to 
  neutralize 
  approximately 
  the 
  effect 
  of 
  a 
  part 
  of 
  the 
  charge 
  

   on 
  the 
  nucleus 
  corresponding 
  to 
  the 
  number 
  of 
  electrons 
  on 
  

   the 
  ring. 
  The 
  values 
  of 
  R(a) 
  show 
  that 
  the 
  effect 
  of 
  outer 
  

   rings 
  on 
  the 
  stability 
  of 
  inner 
  — 
  though 
  greater 
  than 
  the 
  

   effect 
  on 
  the 
  dimensions 
  — 
  is 
  small, 
  but 
  that 
  unless 
  the 
  ratio 
  

   between 
  the 
  radii 
  is 
  very 
  great, 
  the 
  effect 
  of 
  inner 
  rings 
  on 
  

   the 
  stability 
  of 
  outer 
  is 
  considerably 
  greater 
  than 
  to 
  neutralize 
  

   a 
  corresponding 
  part 
  of 
  the 
  charge 
  of 
  the 
  nucleus. 
  

  

  The 
  maximum 
  number 
  of 
  electrons 
  which 
  the 
  innermost 
  

   ring 
  can 
  contain 
  without 
  being 
  unstable 
  is 
  approximately 
  

   equal 
  to 
  that 
  calculated 
  on 
  p. 
  482 
  for 
  a 
  single 
  ring 
  rotating 
  

   round 
  a 
  nucleus. 
  For 
  the 
  outer 
  rings, 
  how 
  r 
  ever, 
  we 
  get 
  

   considerably 
  smaller 
  numbers 
  than 
  those 
  determined 
  by 
  the 
  

   condition 
  (5) 
  if 
  we 
  replace 
  N^ 
  by 
  the 
  total 
  charge 
  on 
  the 
  

   nucleus 
  and 
  on 
  the 
  electrons 
  of 
  inner 
  ring's. 
  

  

  If 
  a 
  system 
  of 
  rings 
  rotating 
  round 
  a 
  nucleus 
  in 
  a 
  single 
  

   plane 
  is 
  stable 
  for 
  small 
  displacements 
  of 
  the 
  electrons 
  

   perpendicular 
  to 
  this 
  plane, 
  there 
  will 
  in 
  general 
  be 
  no 
  stable- 
  

   configurations 
  of 
  the 
  rings, 
  satisfying 
  the 
  condition 
  of 
  the 
  

   constancy 
  of 
  the 
  angular 
  momentum 
  of 
  the 
  electrons, 
  in 
  

   which 
  all 
  the 
  rings 
  are 
  not 
  situated 
  in 
  the 
  plane. 
  An 
  

   exception 
  occurs 
  in 
  the 
  specinl 
  case 
  of 
  two 
  rings 
  containing 
  

   equal 
  numbers 
  of 
  electrons 
  ; 
  in 
  this 
  case 
  there 
  may 
  be 
  a 
  

   stable 
  configuration 
  in 
  which 
  the 
  two 
  rings 
  have 
  equal 
  radii 
  

   and 
  rotate 
  in 
  parallel 
  planes 
  at 
  equal 
  distances 
  from 
  the 
  

   nucleus, 
  the 
  electrons 
  in 
  the 
  one 
  ring 
  being 
  situated 
  just 
  

   opposite 
  the 
  intervals 
  between 
  the 
  electrons 
  in 
  the 
  other 
  

   ring. 
  The 
  latter 
  configuration, 
  however, 
  is 
  unstable 
  if 
  the 
  

   configuration 
  in 
  which 
  all 
  the 
  electrons 
  in 
  the 
  two 
  rings 
  are 
  

   arranged 
  in 
  a 
  single 
  ring 
  is 
  stable. 
  

  

  § 
  3. 
  Constitution 
  of 
  Atoms 
  containing 
  very 
  few 
  Electrons. 
  

  

  As 
  stated 
  in 
  § 
  1, 
  the 
  condition 
  of 
  the 
  universal 
  constancy 
  

   of 
  the 
  angular 
  momentum 
  of 
  the 
  electrons, 
  together 
  with 
  

   the 
  condition 
  of 
  stability, 
  is 
  in 
  most 
  cases 
  not 
  sufficient 
  to 
  

   determine 
  completely 
  the 
  constitution 
  of 
  the 
  system. 
  On 
  

   the 
  general 
  view 
  of 
  formation 
  of 
  atoms, 
  however, 
  and 
  by 
  

   making 
  use 
  of 
  the 
  knowledge 
  of 
  the 
  properties 
  of 
  the 
  

   corresponding 
  elements, 
  it 
  will 
  be 
  attempted, 
  in 
  this 
  section 
  

   and 
  the 
  next, 
  to 
  obtain 
  indications 
  of 
  what 
  configurations 
  of 
  

   the 
  electrons 
  may 
  be 
  expected 
  to 
  occur 
  in 
  the 
  atoms. 
  In 
  

   these 
  considerations 
  we 
  shall 
  assume 
  that 
  the 
  number 
  of 
  

   electrons 
  in 
  the 
  atom 
  is 
  equal 
  to 
  the 
  number 
  which 
  indicates 
  

   the 
  position 
  of 
  the 
  corresponding 
  element 
  in 
  the 
  series 
  of 
  

   elements 
  arranged 
  in 
  order 
  of 
  increasing 
  atomic 
  weights 
  

  

  