100 WHAT IS LIFE 



will retain its identity so long as the nucleus remains 

 intact. 



Moreover, an atom that has lost one or more of 

 its outer electrons will recapture electrons as condi- 

 tions permit. Ionization, as observed especially in 

 gases, is temporary, and the effort is to regain the 

 neutral state. But when the nucleus of the atom 

 loses one or more of its constituents, the atom is 

 transmuted and changed irreparably. 



The nucleus determines the atom. The Bohr 

 theory of the atom accepts the nucleus without having 

 any definite picture to ojfer concerning how the con- 

 stituents of the nucleus are combined in its structure. 



It is a well-known fact that comparatively few 

 of the ninety-two elements are directly involved in 

 the life-process. The chief chemical constituents 

 of the organism are hydrogen, carbon, nitrogen, and 

 oxygen. The human body practically consists of 

 hydrogen, carbon, nitrogen, oxygen, phosphorus, 

 and calcium, only small amounts of other elements 

 being present. The elements that are found in all 

 organisms are: 



Atomic number Atomic weight 

 Hydrogen , 1 1.008 



Carbon 6 12.00 



Nitrogen 7 14.008 



Oxygen 8 16.00 



