THE NATURE OF THE ARGON FAMILY 



OF GASES 



By FREDERICK SODDY, F.R.S. 



University, Glasgow 



The question of the nature of the argon family of gases has 



recently been discussed by Prof. Armstrong and Sir Oliver 



Lodge (Science Progress, 191 3, April, p. 648; and October, 



p. 197). Sir Oliver Lodge defends the accepted view that the 



molecules of these gases consist of single atoms against Prof. 



Armstrong's view that the molecules are polyatomic. Although 



I regard the evidence in favour of the monatomicity of the 



molecule in the case of these gases as beyond dispute, I think 



something can be said also for Prof. Armstrong's theory that 



these gases have an intense affinity — " an affinity so intense that 



it is far beyond anything we have experienced in the case of 



any other element." Where I should join issue with Prof. 



Armstrong is on the question exactly what it is for which the 



argon gases have intense affinity. He regards it as exercised 



between the constituent parts of the molecule, and in 1895, 



when the view was first suggested, no other result was possible 



than that the molecule must therefore necessarily be polyatomic, 



and that the atomic weight and position of the inert gases in 



the periodic table cannot be determined. I will try to show 



that, whilst modern progress seems to leave no loophole of 



escape from the conclusion that the argon gases have molecules 



composed of single atoms, and that these elements are correctly 



represented as occupying a new zero family in the periodic 



table, we can reconcile this with the essentials of Prof. 



Armstrong's view with a distinct gain in clearness as to the 



chemical character of these gases, and the meaning of the 



numbers of the families of the periodic table. 



It is, of course, as Prof. Armstrong is well aware, even more 

 difficult to demonstrate convincingly that the molecule of an 

 element consists of a single atom, and is not merely an 

 hitherto undecomposed collection of atoms, than it is to prove 



654 



