19 , 6 
Perkins: Chlorine Dioxide and Compounds 
737 
borrowing unions. Usually it is convenient to express such a 
union with a separate sign cc , as already noted, to avoid con- 
fusion and show more graphically the valence relations. The 
equivalent sign + — ~, however, is used in formula V. This 
formula shows two chlorate ions in the only position in which 
they would react smoothly with each other. The case of C10 2 
is practically identical. 
0 “ 
I 
— + 4 * 
0 - Cl 
If the above explanation is correct, Cl 2 O s and C1 2 0 4 are un- 
stable due to the inability of bi- or tricovalent chlorine to unite 
with bicovalent oxygen. C10 2 , which contains no bicovalent oxy- 
gen, is therefore formed in reactions from which we might ex- 
pect C1 2 0 4 or C1 2 0 5 . We may suppose that C10 2 contains a 
three-electron bond without denying the strong general tendency 
toward sharing in pairs. In this particular case it seems that 
the pair-sharing tendency does not have an opportunity to mani- 
fest itself. The reasons against any disposition of the odd elec- 
tron other than in one of the bonds have already been given. 
Therefore, it seems highly probable that when an elec- 
tron is removed from one of the oxygen atoms in the ion 
: 0 : Cl : 0 : ( Ox>Cl<xO ), forming the neu- 
tral molecule, : 0 : Cl : 0 . ( O^Cl— 0— ), 
the vacancy caused in the oxygen shell is immediately filled by a 
closer approach to the chlorine shell in such a manner that one 
more electron is shared by the two atoms: 
: 0 : Cl 5 0 : ( 0^C1~0 ). 
Lewis’s notation is here used, the writer’s, which will be fur- 
ther explained in the succeeding section, being given in paren- 
thesis. It is to be noted that the union last mentioned causes 
6 
I 
+ 4 - 
0 - Cl 
0 “ 
