TH E ATOM 99 



Sommerfeld, Max Born, and other leading in- 

 vestigators hold that the nucleus is built up ac- 

 cording to the same laws that govern the building-up 

 of the atom. Sommerfeld expresses the conviction 

 that the nuclei are built up of elementary con- 

 stituents according to the same principles of con- 

 struction; namely, according to the rules of the 

 quantum theory, as the atoms are built up from 

 nuclei and electrons. ^^ 



All are agreed that the nucleus of the atom deter- 

 mines the atom. Irving Langmuir said: "Nearly 

 all of the work on atomic structure has shown 

 that each atom may exist in enormous numbers 

 of different states and that the state of an 

 atom may be modified by nearly every external 

 agent that acts upon it." Again: "Each atom may 

 exist in multitudes of various forms depending 

 on external conditions. The nucleus is the only 

 part of an atom that is absolutely characteristic 

 of it." 



The atom may undergo various vicissitudes — it 

 may be "excited"; various rays may pass through 

 it and perchance work injury to the structure of 

 the atom; it may lose some of its electrons to other 

 atoms; or it may be "stripped" of electrons; it may 

 share its domain with another atom, etc.; but it 



*' Atombau und Spektrallinien, vierte Auflage, 217. 



