Some Dimensions of the Atom. 



875 



charge "E." We can now, presuming the inverse square 

 law holds o-ood when the dimensions are so small, find the 

 force acting on any one of the electrons, and as the atom is 

 stable, so the positive charge must balance 'the negative 

 charges, thus we can find "E" in terms of " e." Let us 

 take the electron e z . 



The diameter of the Helium shell is 2*30 X 10 8 cm. The 

 diameter of the second shell equals the diameter of the Neon 

 shell = 2-58 xl0~ 8 cm. ^ 



Attractive force acting on ^towards the centre = 0Q \ 2 j 



Repulsive force along e z e 1 ^= repulsive force along 



e 2 

 ^ 2 ~(l-]5) 2 +(l-29) 2 ' 

 Now, the component of this force acting away from the 



9 



e 

 centre is given by ^r^ sin 48° 18' = the same component for 



force acting along e z e 2 . 



The force acting between e z e± is t9 .\ KY2 ^ therefore it 

 follows that 



Ke 2e 2 x-7±7 



(l-29) 2 = 

 whence E = l'08<?. 



2-99 



+ 



e 



? 2 



(2•58) 2, 



Fiff. 2. 



Lithium 



For Lithium with an atomic number " 3," we find that 

 E = "83<?. 



Helium, as previously stated, has two electrons arranged 



