﻿of 
  Atoms 
  and 
  Molecules. 
  873 
  

  

  on 
  p. 
  866, 
  we 
  get 
  ^ 
  = 
  13*7 
  . 
  10 
  13 
  . 
  On 
  account 
  o£ 
  the 
  approxi- 
  

   mation 
  introduced 
  the 
  agreement 
  may 
  be 
  considered 
  as 
  

   satisfactory. 
  

  

  The 
  molecules 
  in 
  question 
  may 
  also 
  be 
  formed 
  by 
  the 
  

   combination 
  of 
  a 
  positively 
  and 
  a 
  negatively 
  charged 
  atom. 
  

   As 
  in 
  the 
  case 
  of 
  hydrogen, 
  however, 
  we 
  shall 
  expect 
  to 
  obtain 
  

   two 
  neutral 
  atoms 
  by 
  the 
  breaking 
  up 
  of 
  the 
  molecule. 
  There 
  

   may 
  be 
  another 
  type 
  of 
  molecule, 
  for 
  which 
  this 
  does 
  not 
  hold, 
  

   viz., 
  molecules 
  which 
  are 
  formed 
  in 
  a 
  manner 
  analogous 
  to 
  

   the 
  system 
  consisting 
  of 
  a 
  ring 
  of 
  three 
  electrons 
  and 
  two 
  

   nuclei 
  of 
  charges 
  e 
  and 
  2e, 
  mentioned 
  in 
  the 
  former 
  section. 
  

   As 
  we 
  have 
  seen, 
  the 
  necessary 
  condition 
  for 
  the 
  formation 
  

   of 
  a 
  configuration 
  of 
  this 
  kind 
  is 
  that 
  one 
  of 
  the 
  atoms 
  in 
  the 
  

   molecule 
  is 
  able 
  to 
  bind 
  three 
  electrons 
  in 
  the 
  outer 
  ring. 
  

   According 
  to 
  the 
  theory, 
  this 
  condition 
  is 
  not 
  satisfied 
  for 
  a 
  

   hydrogen 
  or 
  a 
  helium 
  atom, 
  but 
  is 
  for 
  an 
  oxygen 
  atom. 
  With 
  

   the 
  symbols 
  used 
  in 
  Part 
  IT. 
  the 
  configuration 
  suggested 
  for 
  

   the 
  oxygen 
  atom 
  was 
  given 
  by 
  8 
  (4, 
  2, 
  2). 
  From 
  a 
  calculation, 
  

   as 
  that 
  indicated 
  in 
  Part 
  II., 
  we 
  get 
  for 
  this 
  configuration 
  

   W= 
  228*07 
  W 
  , 
  while 
  for 
  the 
  configuration 
  8 
  (4,2,3) 
  we 
  get 
  

   W 
  = 
  228'18W 
  . 
  Since 
  the 
  latter 
  value 
  for 
  W 
  is 
  greater 
  

   than 
  the 
  first, 
  the 
  configuration 
  8 
  (4, 
  2, 
  3) 
  may 
  be 
  considered 
  

   as 
  possible 
  and 
  as 
  representing 
  an 
  oxygen 
  atom 
  with 
  a 
  single 
  

   negative 
  charge. 
  If 
  now 
  a 
  hydrogen 
  nucleus 
  approaches 
  the 
  

   system 
  8 
  (4,2,3) 
  we 
  may 
  expect 
  a 
  stable 
  configuration 
  to 
  be 
  

   formed 
  in 
  which 
  the 
  outer 
  electrons 
  will 
  be 
  arranged 
  approxi- 
  

   mately 
  as 
  in 
  the 
  system 
  mentioned 
  above. 
  In 
  a 
  breaking 
  

   up 
  of 
  this 
  configuration 
  the 
  ring 
  of 
  three 
  electrons 
  will 
  

   remain 
  with 
  the 
  oxygen 
  atom. 
  

  

  Such 
  considerations 
  suggest 
  a 
  possible 
  configuration 
  for 
  a 
  

   water 
  molecule, 
  consisting 
  of 
  an 
  oxygen 
  nucleus 
  surrounded 
  

   by 
  a 
  small 
  ring 
  of 
  4 
  electrons 
  and 
  2 
  hydrogen 
  nuclei 
  situated 
  

   on 
  the 
  axis 
  of 
  the 
  ring 
  at 
  equal 
  distances 
  apart 
  from 
  the 
  first 
  

   nucleus 
  and 
  kept 
  in 
  equilibrium 
  by 
  help 
  of 
  two 
  rings 
  of 
  

   greater 
  radius 
  each 
  containing 
  three 
  electrons 
  ; 
  the 
  latter 
  

   rotate 
  in 
  parallel 
  planes 
  round 
  the 
  axis 
  of 
  the 
  system, 
  and 
  are 
  

   situated 
  relatively 
  to 
  each 
  other 
  so 
  that 
  the 
  electrons 
  in 
  the 
  

   one 
  ring 
  are 
  placed 
  just 
  opposite 
  the 
  interval 
  between 
  the 
  

   electrons 
  in 
  the 
  other. 
  If 
  we 
  imagine 
  that 
  such 
  a 
  system 
  is 
  

   broken 
  up 
  by 
  slowly 
  removing 
  the 
  hydrogen 
  nuclei 
  we 
  should 
  

   obtain 
  two 
  positively 
  charged 
  hydrogen 
  atoms 
  and 
  an 
  oxygen 
  

   atom 
  with 
  a 
  double 
  negative 
  charge, 
  in 
  which 
  the 
  outermost 
  

   electrons 
  will 
  be 
  arranged 
  in 
  two 
  rings 
  of 
  three 
  electrons 
  

   each, 
  rotating 
  in 
  parallel 
  planes. 
  The 
  assumption 
  of 
  such 
  

   a 
  configuration 
  for 
  a 
  water 
  molecule 
  offers 
  a 
  possible 
  

   explanation 
  of 
  the 
  great 
  absorption 
  of 
  water 
  for 
  rays 
  in 
  the 
  

  

  