﻿of 
  Atoms 
  and 
  Molecules. 
  493 
  

  

  correspond 
  to 
  less 
  values 
  for 
  the 
  total 
  energy 
  than 
  the 
  con- 
  

   figurations 
  4 
  (2, 
  1) 
  and 
  4 
  (2, 
  2). 
  

  

  From 
  analogy 
  we 
  get 
  further 
  for 
  the 
  configuration 
  of 
  a 
  

   possible 
  negatively 
  charged 
  atom, 
  

  

  4(2.3^ 
  l 
  a 
  ona 
  i.kk 
  lV=33'6bW 
  . 
  

  

  Comparing 
  the 
  outer 
  ring 
  of 
  the 
  atom 
  considered 
  with 
  the 
  

   ring 
  of 
  a 
  helium 
  atom, 
  we 
  see 
  that 
  the 
  presence 
  of 
  the 
  inner 
  

   ring 
  of 
  two 
  electrons 
  in 
  the 
  beryllium 
  atom 
  markedly 
  changes 
  

   the 
  properties 
  of 
  the 
  outer 
  ring 
  ; 
  partly 
  because 
  the 
  outer 
  

   electrons 
  in 
  the 
  configuration 
  adopted 
  for 
  a 
  neutral 
  beryllium 
  

   atom 
  are 
  more 
  lightly 
  bound 
  than 
  the 
  electrons 
  in 
  a 
  helium 
  

   atom, 
  and 
  partly 
  because 
  the 
  quantity 
  G, 
  which 
  for 
  helium 
  

   is 
  equal 
  to 
  2, 
  for 
  the 
  outer 
  ring 
  in 
  the 
  configuration 
  4(2,2) 
  

   is 
  only 
  equal 
  to 
  1*12. 
  

  

  Since 
  W[4(2,3)]-W[4(2,2)]=0-05Wo, 
  the 
  beryllium 
  

   atom 
  will 
  further 
  have 
  a 
  definite, 
  although 
  very 
  small 
  affinity 
  

   for 
  free 
  electrons. 
  

  

  § 
  4. 
  Atoms 
  containing 
  greater 
  numbers 
  of 
  electrons. 
  

  

  From 
  the 
  examples 
  discussed 
  in 
  the 
  former 
  section 
  it 
  will 
  

   appear 
  that 
  the 
  problem 
  of 
  the 
  arrangement 
  of 
  the 
  electrons 
  

   in 
  the 
  atoms 
  is 
  intimately 
  connected 
  with 
  the 
  question 
  of 
  the 
  

   confluence 
  of 
  two 
  rings 
  of 
  electrons 
  rotating 
  round 
  a 
  nucleus 
  

   outside 
  each 
  other, 
  and 
  satisf}dng 
  the 
  condition 
  of 
  the 
  

   universal 
  constancy 
  of 
  the 
  angular 
  momentum. 
  Apart 
  from 
  

   the 
  necessary 
  conditions 
  of 
  stability 
  for 
  displacements 
  of 
  the 
  

   electrons 
  perpendicular 
  to 
  the 
  plane 
  of 
  the 
  orbits, 
  the 
  present 
  

   theory 
  gives 
  very 
  little 
  information 
  on 
  this 
  problem. 
  It 
  

   seems, 
  however, 
  possible 
  by 
  the 
  help 
  of 
  simple 
  considerations 
  

   to 
  throw 
  some 
  light 
  on 
  the 
  question. 
  

  

  Let 
  us 
  consider 
  two 
  rings 
  rotating 
  round 
  a 
  nucleus 
  in 
  a 
  

   single 
  plane, 
  the 
  one 
  outside 
  the 
  other. 
  Let 
  us 
  assume 
  that 
  

   the 
  electrons 
  in 
  the 
  one 
  ring 
  act 
  upon 
  the 
  electrons 
  in 
  the 
  

   other 
  as 
  if 
  the 
  electric 
  charge 
  were 
  uniformly 
  distributed 
  

   along 
  the 
  circumference 
  of 
  the 
  ring, 
  and 
  that 
  the 
  rings 
  with 
  

   this 
  approximation 
  satisfy 
  the 
  condition 
  of 
  the 
  angular 
  

   momentum 
  of 
  the 
  electrons 
  and 
  of 
  stability 
  for 
  displacements 
  

   perpendicular 
  to 
  their 
  plane. 
  

  

  Now 
  suppose 
  that, 
  by 
  help 
  of 
  suitable 
  imaginary 
  extra- 
  

   neous 
  forces 
  acting 
  parallel 
  to 
  the 
  axis 
  of 
  the 
  rings, 
  we 
  pull 
  

   the 
  inner 
  ring 
  slowly 
  to 
  one 
  side. 
  During 
  this 
  process, 
  on 
  

   account 
  of 
  the 
  repulsion 
  from 
  the 
  inner 
  ring, 
  the 
  outer 
  will 
  

   move 
  to 
  the 
  opposite 
  side 
  of 
  the 
  original 
  plane 
  of 
  the 
  rings. 
  

  

  Phil. 
  Mag. 
  S. 
  6. 
  Vol. 
  2$. 
  No. 
  153. 
  Sept. 
  1913. 
  2 
  L 
  

  

  