THE STRUCTURE OF ATOMS AND ITS 

 BEARING ON CHEMICAL VALENCE 



BY 



IRVING LANGMUIR 

 General Electric Company 



ACCORDING to the well-established Rutherford-Bohr 

 theory, all the positive electricity in an atom is concen- 

 trated in a nucleus at its center. The dimensions of this 

 nucleus are negligibly small compared with those of the 

 rest of the atom, its diameter being of the order of o.ooooi 

 of that of the atom. The charge on the nucleus is an inte- 

 gral multiple of the charge of an electron but of course 

 opposite in sign. The remainder of the atom consists of 

 electrons arranged in space about the nucleus, the normal 

 number of such electrons (called the atomic number) 

 being equal to the number of unit positive charges on the 

 nucleus, so that the atom as a whole is electrically neutral. 

 If the number of electrons in the atom exceeds the atomic 

 number we have a negatively charged atom or ion while 

 in the reverse case a positively charged atom or ion re- 

 sults. The atomic number of any element has been found 

 to be equal to the ordinal number of the element in the 

 periodic table. Thus hydrogen has the atomic number 

 one, helium 2, lithium 3, carbon 6, neon 10, chlorine 17, 

 nickel 28, silver 47, cerium, 58, tungsten 74, radium 88, 

 and uranium 92. The atomic numbers can be determined 



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