ELECTRONS 95 



course of degradation rather than another. This is 

 true of certain of the radioactive elements, where atoms 

 of the same atomic weight as well as of the same atomic 

 number may follow different sequences of radioactive 

 changes. 



Whenever the number of planetary electrons about 

 a nucleus does not correspond to the atomic number, 

 then the atomic system is electrically charged, that is, 

 "ionized/* Its further activities are due to that charge 

 and the atom is under the urge of restoring a state of 

 electrical equilibrium. Of such activities there are too 

 many for present mention. They accompany any de- 

 rangement of the planetary electrons and to them are 

 due many of the phenomena of light and X-rays. 



A current of electricity exists whenever there is a 

 stream of electrons from one point to another. In con- 

 duction through gases the gas must be ionized before it 

 becomes conducting. Its molecules must be split apart 

 in some manner which will result in the formation of 

 ions, that is, atomic or molecular systems which have 

 more or less than the normal number of electrons. Such 

 ionization may be accomplished in a number of ways, 

 by the action of ultra-violet light, by exposure of the 

 gas to X-rays, by impacts with swiftly moving electrons 

 or alpha particles from radioactive substances, or by 

 collision with swiftly moving free electrons or ions how- 

 ever obtained. Under these conditions some of the 

 gaseous molecules lose by impact planetary electrons 

 and thus become positive ions. The freed electrons 

 immediately take up their way toward the positive elec- 

 trode and the positive ions take the opposite way 



