﻿322 
  Dr. 
  L. 
  Yegard 
  on 
  the 
  X-Ray 
  Spectra 
  

  

  which 
  we 
  do 
  not 
  know. 
  Now 
  the 
  forces 
  which 
  are 
  engaged 
  

   in 
  the 
  chemical 
  binding 
  of 
  elements 
  do 
  not 
  act 
  on 
  a 
  single 
  

   electron 
  as 
  in 
  the 
  case 
  of 
  an 
  ionizing 
  agency, 
  but 
  much 
  more 
  

   on 
  the 
  ring 
  as 
  a 
  unity. 
  From 
  this 
  consideration 
  it 
  might 
  

   be 
  more 
  natural 
  to 
  take 
  the 
  energy 
  necessary 
  to 
  remove 
  an 
  

   electron 
  when 
  all 
  the 
  other 
  electrons 
  of 
  the 
  ring 
  were 
  

   removed 
  simultaneously. 
  According 
  to 
  Bohr 
  this 
  energy 
  

   is 
  equal 
  to 
  the 
  kinetic 
  energy 
  of 
  the 
  electron, 
  and 
  thus 
  

   elements 
  with 
  the 
  more 
  slowly 
  moving 
  electrons 
  are 
  the 
  

   more 
  electropositive. 
  Equation 
  (7) 
  gives 
  for 
  this 
  energy 
  

  

  w=hR- 
  —-^ 
  > 
  

  

  n 
  2 
  

  

  where 
  approximately 
  W=p 
  andp 
  is 
  the 
  number 
  of 
  electrons 
  

   in 
  the 
  surface 
  ring 
  ; 
  KR 
  is 
  the 
  value 
  of 
  the 
  energy 
  wr 
  for 
  

   hydrogen. 
  

  

  J" 
  = 
  (p-Sj>) 
  2 
  =* 
  (27) 
  

  

  Let 
  us 
  first 
  consider 
  the 
  variation 
  of 
  a 
  for 
  elements 
  which 
  

   have 
  the 
  same 
  number 
  of 
  ring 
  systems 
  and 
  only 
  differ 
  with 
  

   regard 
  to 
  the 
  number 
  of 
  electrons 
  in 
  the 
  external 
  ring. 
  

   Suppose, 
  e. 
  </., 
  that 
  we 
  consider 
  the 
  elements 
  from 
  Na 
  

   to 
  CI. 
  For 
  such 
  a 
  series 
  the 
  quant 
  number 
  n 
  is 
  constant 
  

   and 
  a 
  consequently 
  proportional 
  to 
  (p 
  — 
  S 
  p 
  ) 
  2 
  , 
  and 
  we 
  can 
  easily 
  

   see 
  that 
  <r 
  increases 
  with 
  increasing 
  values 
  of 
  p 
  by 
  forming 
  

  

  <rp 
  + 
  i-<rp 
  = 
  {2p 
  + 
  l-(&p+i-$p)}{l-{Sp+i-Sp)}' 
  

  

  As 
  both 
  factors 
  on 
  the 
  right 
  side 
  are 
  positive, 
  cr 
  p+1 
  > 
  a 
  v 
  . 
  

  

  If 
  o- 
  could 
  be 
  taken 
  to 
  represent 
  the 
  electronegativity, 
  the 
  

   elements 
  in 
  each 
  such 
  group 
  would 
  pass 
  from 
  electropositive 
  

   to 
  more 
  electronegative 
  as 
  we 
  proceed 
  towards 
  increasing 
  

   atomic 
  numbers. 
  

  

  Let 
  us 
  next 
  consider 
  elements 
  which 
  are 
  chemicalty 
  

   related 
  ; 
  such 
  elements 
  have 
  the 
  same 
  value 
  of 
  p. 
  As 
  we 
  

   pass 
  from 
  low 
  to 
  high 
  atomic 
  numbers, 
  the 
  quant 
  number 
  n 
  

   will 
  increase 
  and 
  the 
  value 
  of 
  a 
  will 
  diminish. 
  Thus 
  elements 
  

   of 
  the 
  same 
  chemical 
  family 
  should 
  be 
  more 
  electropositive 
  

   as 
  we 
  pass 
  towards 
  increasing 
  atomic 
  numbers, 
  which 
  is 
  

   indeed 
  a 
  well-known 
  property 
  of 
  the 
  elements. 
  

  

  The 
  Electric 
  Conductivity. 
  

  

  There 
  can 
  probably 
  be 
  no 
  doubt 
  that 
  the 
  electric 
  conductivity 
  

   in 
  some 
  way 
  or 
  other 
  is 
  related 
  to 
  the 
  energy 
  which 
  binds 
  

   the 
  electrons 
  of 
  the 
  surface 
  system. 
  Introducing 
  a 
  quantity 
  

  

  