Influence of Atomic Weight, 



319 



in which is represented the affinity for H (which may be consi- 

 sidered as a highly positive metal in the gaseous state) of the 

 various elements from F to Si ; and it is seen that these affi- 

 nities diminish from F to Si in such a way that each element is 

 capable of decomposing the hydrogen-compounds of all the 

 succeeding elements. 



(b) If the statement contained in (a) be true, then the heat 

 evolved {for 1 atom CI) in the combination of the different 

 elements with CI to form normal chlorides ivill increase from F 

 to Cs, the heat evolved on the combination of 2 elements 

 being a measure of their affinity for one another. This is 

 represented in the following Table*: — 



Univalent 



Bivalent 



Trivalent 



•Quadrivalent... 



Trivalent 



Bivalent 



F = ? 

 =-7-6 

 N = ? 

 C = ? 

 B =361 

 Be = ? 

 Li =94-0 



CI = ? 

 s = ? 

 P =25-2 

 Si =39-4 

 Al =52-0 

 Mg=75-5 

 Na =97-7 



Ca = 84-8 

 K =104-6 



Univalent 



Br=? 



Se = ? 

 As =240 

 76 



Yt=? 

 Sr =92-3 

 Rb = ? 



I =? 

 Te= ? 

 Sb=30-4 



Di= ? 

 Ba=97-1 



Cs= ? 



(c) The arithmetical mean of the atomic weights of the two 

 elements with equal but opposite affinities is approximately equal 

 to 76. Thus :— 



F = 19 + Cs = 133 7r 0=16 + Ba=137 „ aK 

 = 76, =/6-5, 



N=14 + Di = 138_ 



2 

 Te = 1284 Mg = 24 



2 



76, 



= 76, 



I=127 + ]S T a = 23 



= 75. 



Sl = 122 + Al = 27-4 -, K 

 = /4-5< 



(d) The melting- and boiling-points of the elements increase 

 from F to Si with rising atomic weight and rising atomicity; 

 and from that point to Cs they diminish with rising atomic iveiglit 

 and falling atomicity. (Compare with Table on p. 315.) 



In his original paper, Woechter shows that similar relations 

 hold also as regards the specific heat and specific gravity of 

 these elements. 



* The numbers given in this Table are chiefly those determined by 

 Berthelot and Thomsen, and were not given in Woeckter's original paper. 



