﻿of 
  Atoms 
  and 
  Molecules. 
  477 
  

  

  observed 
  example 
  of 
  a 
  process 
  of 
  this 
  kind, 
  an 
  a 
  particle 
  on 
  

   this 
  view 
  being 
  identical 
  with 
  the 
  nnclens 
  of 
  a 
  helium 
  atom. 
  

  

  On 
  account 
  of 
  the 
  small 
  dimensions 
  of 
  the 
  nucleus, 
  its 
  

   internal 
  structure 
  will 
  not 
  be 
  of 
  sensible 
  influence 
  on 
  the 
  

   constitution 
  of 
  the 
  cluster 
  of 
  electrons, 
  and 
  consequently 
  

   will 
  have 
  no 
  effect 
  on 
  the 
  ordinary 
  physical 
  and 
  chemical 
  

   properties 
  of 
  the 
  atom. 
  The 
  latter 
  properties 
  on 
  this 
  theory 
  

   will 
  depend 
  entirely 
  on 
  the 
  total 
  charge 
  and 
  mass 
  of 
  the 
  

   nucleus 
  ; 
  the 
  internal 
  structure 
  of 
  the 
  nucleus 
  will 
  be 
  of 
  

   influence 
  only 
  on 
  the 
  phenomena 
  of 
  radioactivity. 
  

  

  From 
  the 
  result 
  of 
  experiments 
  on 
  large-angle 
  scattering 
  

   of 
  a-rays, 
  Rutherford 
  * 
  found 
  an 
  electric 
  charge 
  on 
  the 
  

   nucleus 
  corresponding 
  per 
  atom 
  to 
  a 
  number 
  of 
  electrons 
  

   approximately 
  equal 
  to 
  half 
  the 
  atomic 
  weight. 
  This 
  result 
  

   seems 
  to 
  bo 
  in 
  agreement 
  with 
  the 
  number 
  of 
  electrons 
  per 
  

   atom 
  calculated 
  from 
  experiments 
  on 
  scattering 
  of 
  Rontgen 
  

   radiation 
  f 
  . 
  The 
  total 
  experimental 
  evidence 
  supports 
  the 
  

   hypothesis 
  % 
  that 
  the 
  actual 
  number 
  of 
  electrons 
  in 
  a 
  neutral 
  

   atom 
  with 
  a 
  few 
  exceptions 
  is 
  equal 
  to 
  the 
  number 
  whicn 
  

   indicates 
  the 
  position 
  of 
  the 
  corresponding 
  element 
  in 
  the 
  

   series 
  of 
  elements 
  arranged 
  in 
  order 
  of 
  increasing 
  atomic 
  

   weight. 
  For 
  example 
  on 
  this 
  view, 
  the 
  atom 
  of 
  oxygen 
  

   which 
  is 
  the 
  eighth 
  element 
  of 
  the 
  series 
  has 
  eight 
  electrons 
  

   and 
  a 
  nucleus 
  carrying 
  eight 
  unit 
  charges. 
  

  

  We 
  shall 
  assume 
  that 
  the 
  electrons 
  are 
  arranged 
  at 
  equal 
  

   angular 
  intervals 
  in 
  coaxial 
  rings 
  rotating 
  round 
  the 
  nucleus. 
  

   In 
  order 
  to 
  determine 
  the 
  frequency 
  and 
  dimensions 
  of 
  the 
  

   rings 
  we 
  shall 
  use 
  the 
  main 
  hypothesis 
  of 
  the 
  first 
  paper, 
  

   viz. 
  : 
  that 
  in 
  the 
  permanent 
  state 
  of 
  an 
  atom 
  the 
  angular 
  

   momentum 
  of 
  every 
  electron 
  round 
  the 
  centre 
  of 
  its 
  orbit 
  is 
  

  

  equal 
  to 
  the 
  universal 
  value 
  -— 
  , 
  where 
  h 
  is 
  Planck's 
  constant. 
  

  

  We 
  shall 
  take 
  as 
  a 
  condition 
  of 
  stability, 
  that 
  the 
  total 
  

   energy 
  of 
  the 
  system 
  in 
  the 
  configuration 
  in 
  question 
  is 
  less 
  

   than 
  in 
  any 
  neighbouring 
  configuration 
  satisfying 
  the 
  same 
  

   condition 
  of 
  the 
  angular 
  momentum 
  of 
  the 
  electrons. 
  

  

  If 
  the 
  charge 
  on 
  the 
  nucleus 
  and 
  the 
  number 
  of 
  electrons 
  

   in 
  the 
  different 
  rings 
  is 
  known, 
  the 
  condition 
  in 
  regard 
  to 
  

   the 
  angular 
  momentum 
  of 
  the 
  electrons 
  will, 
  as 
  shown 
  in 
  

   § 
  2 
  i 
  completely 
  determine 
  the 
  configuration 
  of 
  the 
  system, 
  

   i. 
  e., 
  the 
  frequency 
  of 
  revolution 
  and 
  the 
  linear 
  dimensions 
  of 
  

   the 
  rings. 
  Corresponding 
  to 
  different 
  distributions 
  of 
  the 
  

  

  * 
  Comp. 
  also 
  Geiger 
  and 
  Marsden, 
  Phil. 
  Mag. 
  xxv. 
  p. 
  604 
  (1913). 
  

   t 
  Comp. 
  C. 
  G. 
  Barkla, 
  Phil. 
  Mag. 
  xxi. 
  p. 
  648 
  (1911). 
  

   J 
  Comp. 
  A. 
  v. 
  d. 
  Broek, 
  Phys. 
  Zeitschr. 
  xiv. 
  p. 
  32 
  (1913). 
  

   Phil. 
  Mag. 
  S. 
  6. 
  Vol. 
  26. 
  No. 
  1.53. 
  Sept. 
  1913, 
  2 
  K 
  

  

  