FOUNDATION FACTS AND PRINCIPLES n 



atomic weights, 1 together with the recently discovered radium and 

 radio activity, and the evidences 2 of accomplished transformation 

 of one element into another, strongly indicate a common origin 

 for different elements, and lend to the subject a present-day in- 

 terest as intense as ever moved the alchemist to try to turn the 

 baser metals into gold. 



1 It is worth while to note some relations that exist between the monovalent 

 elements fluorin, chlorin, bromin, iodin; between the bivalent elements oxygen, 

 sulfur, selenium, molybdenum; between the trivalent (or pentavalent) nitrogen, 

 phosphorus, arsenic, antimony; and also between the tetravalent carbon, silicon, 

 titanium, and germanium: 



Fluorin Chlorin Bromin Iodin 



F = i9 01 = 35.5 Br = 8o 1 = 127 



HF HC1 HBr HI 



Oxygen Sulfur Selenium Molybdenum 



O = 16 8 = 32.1 Se = 79.2 Mo = 96 

 H 2 O H 2 S H 2 Se 



H 2 SeO 4 H 2 MoO 4 



Nitrogen Phosphorus Arsenic Antimony 



N = 14 P = 31 As = 75 Sb = 120.2 



NH 3 PH 3 AsH 3 SbH 3 . 



N 2 O 5 P 2 O 5 As 2 O 6 Sb 2 O 6 



Carbon Silicon Titanium Germanium 



C = 12 Si = 28.4 Ti = 48 Ge = 72.5 



CO 2 SiO 2 TiO 2 GeO 2 



Aside from the similarity of valence and other properties and of compounds 

 formed, there is interest in the relation of atomic weights, especially in the second 

 and fourth groups, and, even in the fact that the atomic weight of antimony is so 

 nearly the sum of the other three in the group. 



2 In 1907 Ramsay and Cameron, of England, reported that they had reduced 

 copper, in the presence of radium emanation, into other elements of the same series: 

 potassium, sodium, lithium. (See Nature, July, 1907, and Journal of the Chemical 

 Society, September, 1907.) The correctness of Ramsay and Cameron's experiments 

 has been called in question by Mme. Curie and Mile. Gleditsch; Comptes rendes, 

 147, 345 (1908); Science, December 4, 1908. 



