732 The Philippine Journal of Science 1921 
attacked this difficulty from the physicist’s viewpoint of min- 
imum potential energy.’ The fuller publication of calculations 
on the stability of various molecules will be interesting and 
valuable, but in the present state of physical knowledge can 
hardly be expected to cover completely the point now under 
discussion. From the chemist’s standpoint a few general ten- 
dencies may be found which may serve to explain why Cl,O, 
ClO,, and Cl,0, are relatively stable as compared to Cl,O,, 
Cl,0,, and Cl,0,. 
THE TENDENCY TO SHARE ELECTRONS 
“Chlorine, like fluorine, tends to form negative ions, but it differs from 
fluorine in that it can share electrons with oxygen, especially if the molecule 
takes up electrons from some more strongly electro-positive element. It 
shows a tendency like phosphorus and sulfur to share all 4 pairs of its 
electrons, if it has to share any.” ® 
It seems to the writer more consistent with the facts to con- 
sider the tendency to share electrons as a mutual tendency which 
two atoms may have, rather than a single property of one of 
them. It seems that electrons can be shared only when an 
approximate equality exists between what may be called the 
electron binding strengths of the two atoms. The exact interpre- 
tation of this in terms of mathematical physics depends on 
one’s ideas of the structure of the atom; but regardless of such 
disputed hypotheses, it may be considered as an empirical gene- 
ralization standing on its own merits, A rough physical inter- 
Pretation is that a very unsymmetrical union such as Ne<O 
€ : Ne : O : ) is extremely unstable because, if it should 
momentarily take place, the shared pair would be held too close 
to the neon kernel for a strong attraction to exist between 
the shared pair and the weaker oxygen kernel. Therefore 
a very slight disturbance would separate the atoms in the form 
Ne + +o ( : Ne : + 0: ) and thus lead to the 
formation of stable oxygen molecules, O=O | ( 0 3 0 : ). 
In this symmetrical molecule neither kernel pulls the shared 
electrons beyond the control of the other kernel. 
"Chemical and Met. Eng. 24 (1921) 554. 
* Langmuir, I., Journ. Am. Chem. Soc. 41 (1919) 923.: 
