﻿496 
  Dr. 
  N. 
  Bohr 
  on 
  the 
  Constitution 
  

  

  for 
  N^IO 
  the 
  latter 
  configuration, 
  however, 
  will 
  be 
  stable 
  

   for 
  displacements 
  of 
  the 
  electrons 
  perpendicular 
  to 
  the 
  plane 
  

   of 
  their 
  orbits. 
  A 
  ring 
  of 
  16 
  electrons 
  will 
  not 
  he 
  stable 
  

   unless 
  N 
  is 
  very 
  great 
  ; 
  but 
  in 
  such 
  a 
  case 
  the 
  simple 
  

   considerations 
  mentioned 
  above 
  do 
  not 
  apply. 
  

  

  The 
  confluence 
  of 
  two 
  rings 
  of 
  equal 
  number 
  of 
  electrons, 
  

   which 
  rotate 
  round 
  a 
  nucleus 
  of 
  charge 
  Ne 
  outside 
  a 
  ring 
  of 
  

   n 
  electrons 
  already 
  bound, 
  must 
  be 
  expected 
  to 
  take 
  place 
  

   more 
  easily 
  than 
  the 
  confluence 
  of 
  two 
  similar 
  rings 
  rotating 
  

   round 
  a 
  nucleus 
  of 
  charge 
  (N 
  — 
  n)e 
  ; 
  for 
  the 
  stability 
  of 
  the 
  

   rings 
  for 
  a 
  displacement 
  perpendicular 
  to 
  their 
  plane 
  will 
  

   (see 
  § 
  2) 
  be 
  smaller 
  in 
  the 
  first 
  than 
  in 
  the 
  latter 
  case. 
  This 
  

   tendenc} 
  T 
  for 
  stability 
  to 
  decrease 
  for 
  displacements 
  perpen- 
  

   dicular 
  to 
  the 
  plane 
  of 
  the 
  ring 
  will 
  be 
  especially 
  marked 
  for 
  

   the 
  outer 
  rings 
  of 
  electrons 
  of 
  a 
  neutral 
  atom. 
  In 
  the 
  latter 
  

   case 
  we 
  must 
  expect 
  the 
  confluence 
  of 
  rings 
  to 
  be 
  greatly 
  

   facilitated, 
  and 
  in 
  certain 
  cases 
  it 
  may 
  even 
  happen 
  that 
  the 
  

   number 
  of 
  electrons 
  in 
  the 
  outer 
  ring 
  may 
  be 
  greater 
  than 
  

   in 
  the 
  next, 
  and 
  that 
  the 
  outer 
  ring 
  may 
  show 
  deviations 
  

   from 
  the 
  assumption 
  of 
  1, 
  2, 
  4, 
  8 
  electrons 
  in 
  the 
  rings, 
  

   e. 
  g. 
  the 
  configurations 
  5 
  (2, 
  3) 
  and 
  6 
  (2, 
  4) 
  instead 
  of 
  the 
  con- 
  

   figurations 
  5 
  (2,2,1) 
  and 
  6 
  (2,2,2). 
  We 
  shall 
  here 
  not 
  discuss 
  

   further 
  the 
  intricate 
  question 
  of 
  the 
  arrangement 
  of 
  the 
  

   electrons 
  in 
  the 
  outer 
  ring. 
  In 
  the 
  scheme 
  given 
  below 
  the 
  

   number 
  of 
  electrons 
  in 
  this 
  ring 
  is 
  arbitrarily 
  put 
  equal 
  to 
  

   the 
  normal 
  valency 
  of 
  the 
  corresponding 
  element 
  ; 
  i. 
  e. 
  for 
  

   electronegative 
  and 
  electropositive 
  elements 
  respectively 
  the 
  

   number 
  of 
  hydrogen 
  atoms 
  and 
  twice 
  the 
  number 
  of 
  oxygen 
  

   atoms 
  with 
  which 
  one 
  atom 
  of 
  the 
  element 
  combines. 
  

  

  Such 
  an 
  arrangement 
  of 
  the 
  outer 
  electrons 
  is 
  suggested 
  

   by 
  considerations 
  of 
  atomic 
  volumes. 
  As 
  is 
  well 
  known, 
  the 
  

   atomic 
  volume 
  of 
  the 
  elements 
  is 
  a 
  periodic 
  function 
  of 
  the 
  

   atomic 
  weights. 
  If 
  arranged 
  in 
  the 
  usual 
  way 
  according 
  to 
  

   the 
  periodic 
  system, 
  the 
  elements 
  inside 
  the 
  same 
  column 
  

   have 
  approximately 
  the 
  same 
  atomic 
  volume, 
  while 
  this 
  

   volume 
  changes 
  considerably 
  from 
  one 
  column 
  to 
  another, 
  

   being 
  greatest 
  for 
  columns 
  corresponding 
  to 
  the 
  smallest 
  

   valency 
  1 
  and 
  smallest 
  for 
  the 
  greatest 
  valency 
  4. 
  An 
  

   approximate 
  estimate 
  of 
  the 
  radius 
  of 
  the 
  outer 
  ring 
  of 
  a 
  

   neutral 
  atom 
  can 
  be 
  obtained 
  by 
  assuming 
  that 
  the 
  total 
  

   force 
  due 
  to 
  the 
  nucleus 
  and 
  the 
  inner 
  electrons 
  is 
  equal 
  to 
  

   that 
  from 
  a 
  nucleus 
  of 
  charge 
  ne 
  9 
  where 
  n 
  is 
  the 
  number 
  of 
  

   electrons 
  in 
  the 
  ring. 
  Putting 
  F 
  = 
  n 
  — 
  s 
  n 
  in 
  the 
  equation 
  (1) 
  

   on 
  p. 
  478, 
  and 
  denoting 
  the 
  value 
  of 
  a 
  for 
  n 
  = 
  l 
  by 
  a 
  , 
  we 
  

   get 
  for 
  7i 
  — 
  2, 
  a 
  = 
  0'b7a 
  ; 
  for 
  n-='3, 
  a 
  = 
  0'41a 
  ; 
  and 
  for 
  

   n 
  = 
  4, 
  a 
  = 
  0'33« 
  . 
  Accordingly 
  the 
  arrangement 
  chosen 
  

  

  