CONSTITUTION OF THE ATOM—EVE. 189 
determination of the nucleus charges of the atoms of most of the ele- 
ments. He bombarded the elements, one after the other, by electrons 
as cathode rays, reflected the resulting Réntgen rays from a crystal, 
and measured the wave-lengths of one or other of the principal (K or 
L, hard or soft) radiations. 
In this manner he found 
n= A(N —B)?, 
where n is the frequency of vibration, N the nucleus electronic charge, 
necessarily a whole number, and A and B are determined constants. 
In this manner he has found the atomic numbers N of all the known 
elements from aluminium 13 to gold 79. There appear to be but two 
or three elements not yet found by the chemists. These experimental 
results bear out well a view first propounded by van den Broek, that 
each element has an atomic number, an integer representing its place 
in the periodic table (H 1, He 2, Li 3, Be 4, Bo 5, C 6, and so forth). 
The atomic weight is not an exact integer, nor of such fundamental 
character as the atomic number. There will be further reference to 
this point later. 
12. Rutherford has extended Moseley’s method and results to the 
crystal reflection of the gamma rays from a radiant (Ra B), and 
determined the wave lengths of many lines, in particular of the two 
strongest. He has bombarded lead with Ra B rays and found the 
wave lengths of the radiation stimulated in the lead. He found that 
Radium B and lead gave the same spectrum, indicating that they 
have the same atomic number, 82. Hence he deduced the atomic 
numbers of all the radiants in the uranium-radium family. His 
results are worth repeating. 
| 
Atomic Atomic 
Radiant. Rays. oe weight Radiant. Rays. Atomic weight 
(about). v (about). 
Uramgm: Tito 22tel a 92 | 238.5 Radigm Ais}. os f8o: a 84 | 218.5 
Wranim xe Doss... B 90 | 234.5 Radiim) Be esses. 82 | 214.5 
Uranium X 2....--.- B 91 | 234.5 Radium Os 3b. : a,B 83 | 214.5 
rani 222) 5 45-2=2 a 92 | 234.5 15 Cob phat il Dee eee 82 | 210.5 
dormrm Ie FA ea) a 90 | 230.5 Radium! His. sti . B 83 | 210.5 
TERROR TTI as seis Se iceie a 88 | 226.5 Radigmib ses ose ese a 84 | 210.5 
Radium Em......... a 86 | 222.5 Leadis ei EL Ie Sse seo. 82 | 206.5 (207.1) 
13. All of these results are in harmony with the wonderful advances 
in radiochemistry due to Soddy, Fajans, Von Hevesy, and others. It 
has been found that when a radiant emits an alpha particle or helium 
nucleus, the chemical properties of the newly formed radiant differ 
from the old. A fresh element is formed, a different valency results, 
and the new radiant, relative to the old, is two columns to the left in 
the periodic table. The atomic number has decreased 2 and the 
atomic weight about 4. But when a radiant ejects a beta particle or 
electron, again there is a new radiant with different valency and 
