﻿320 
  Dr. 
  L. 
  Vegard 
  on 
  the 
  Ik-Ray 
  Spectra 
  

  

  we 
  pass 
  from 
  the 
  rare 
  earths 
  ; 
  new 
  electrons 
  are 
  added 
  as 
  

   before 
  to 
  the 
  surface 
  system, 
  and 
  we 
  get 
  systems 
  of 
  the 
  same 
  

   type 
  as 
  those 
  of 
  the 
  two 
  long 
  series. 
  

  

  The 
  whole 
  system 
  here 
  shortly 
  sketched 
  is 
  graphically 
  re- 
  

   presented 
  in 
  fig. 
  2. 
  Along 
  the 
  horizontal 
  axis 
  the 
  elements 
  

   are 
  arranged 
  in 
  the 
  order 
  of 
  increasing 
  atomic 
  numbers. 
  

   The 
  principle 
  adopted, 
  that 
  an 
  electronic 
  system 
  once 
  formed 
  

   is 
  kept 
  throughout 
  the 
  whole 
  series 
  of 
  elements, 
  makes 
  it 
  

   natural 
  to 
  represent 
  an 
  electron 
  by 
  a 
  horizontal 
  line. 
  These 
  

   lines 
  are 
  arranged 
  into 
  groups, 
  and 
  each 
  group 
  represents 
  an 
  

   electronic 
  ring 
  system. 
  The 
  arrangement 
  of 
  electrons 
  for 
  

   a 
  certain 
  element 
  is 
  got 
  by 
  drawing 
  a 
  vertical 
  line 
  from 
  the 
  

   place 
  of 
  the 
  element 
  on 
  the 
  horizontal 
  axis. 
  The 
  points 
  

   of 
  intersection 
  with 
  the 
  horizontal 
  lines 
  give 
  the 
  number 
  of 
  

   electrons 
  and 
  their 
  arrangement 
  into 
  ring 
  systems. 
  

  

  On 
  the 
  Electron 
  Affinity 
  of 
  the 
  Elements. 
  

  

  When 
  we 
  pass 
  from 
  elements 
  that 
  follow 
  an 
  inert 
  gas, 
  we 
  

   begin 
  with 
  the 
  strong 
  electropositive 
  elements, 
  and 
  as 
  we 
  

   pass 
  on 
  they 
  become 
  more 
  electronegative. 
  The 
  transition 
  

   from 
  electronegative 
  to 
  electropositive 
  elements 
  may 
  either 
  

   take 
  place 
  by 
  the 
  passage 
  through 
  an 
  inert 
  gas 
  or 
  by 
  passing 
  

   the 
  groups 
  Fe 
  Co 
  Ni, 
  Ru 
  Rh 
  Pd, 
  and 
  Os 
  Ir 
  Pt. 
  In 
  our 
  

   system 
  the 
  strong 
  electropositive 
  elements 
  set 
  in 
  with 
  the 
  

   formation 
  of 
  a 
  new 
  surface 
  ring. 
  

  

  It 
  might 
  now 
  be 
  asked 
  which 
  quantity 
  might 
  rightly 
  be 
  

   selected 
  to 
  express 
  the 
  chemical 
  electro-affinity. 
  

  

  The 
  idea 
  would 
  naturally 
  suggest 
  itself 
  that 
  the 
  electron 
  

   affinity 
  is 
  measured 
  by 
  the 
  energy 
  necessary 
  to 
  remove 
  an 
  

   electron 
  from 
  the 
  external 
  ring. 
  This, 
  however, 
  is 
  identical 
  

   with 
  the 
  energy 
  necessary 
  to 
  ionize 
  the 
  atom 
  and 
  is 
  propor- 
  

   tional 
  to 
  the 
  ionizing 
  potential, 
  which 
  is 
  no 
  measure 
  of 
  the 
  

   chemical 
  electronegativity 
  *. 
  

  

  Nor 
  can 
  we 
  take 
  the 
  energy 
  which 
  binds 
  an 
  additional 
  

   electron 
  ; 
  for 
  the 
  experiments 
  of 
  J. 
  J. 
  Thomson 
  f 
  on 
  positive 
  

   rays 
  have 
  shown 
  that 
  the 
  power 
  of 
  an 
  atom 
  to 
  bind 
  electrons 
  

   does 
  not 
  follow 
  the 
  chemical 
  electronegativity. 
  

  

  I 
  think 
  the 
  explanation 
  of 
  these 
  facts 
  may 
  be 
  found 
  in 
  the 
  

   following 
  considerations. 
  The 
  electrons 
  forming 
  part 
  of 
  a 
  

   normal 
  atomic 
  ring 
  system 
  are 
  not 
  to 
  be 
  considered 
  as 
  free 
  

   electrons, 
  but 
  as 
  linked 
  together 
  in 
  some 
  way, 
  the 
  nature 
  of 
  

  

  * 
  See 
  J. 
  Stark, 
  " 
  Ionisierung 
  der 
  chemischen 
  Eleniente 
  durch 
  Elektro- 
  

   nenstoss," 
  Jahrb. 
  d. 
  Had. 
  u. 
  Elektronik, 
  xiii. 
  

  

  f 
  Sir 
  J. 
  J. 
  Thomson, 
  < 
  Rays 
  of 
  Positive 
  Electricity,' 
  p. 
  40 
  (1913), 
  

   p. 
  395 
  (1916). 
  

  

  