. , , , . , , 10-14 10-15 ( 10-10).
.
() , , mp =1,6726 10-27 1836 me, me . (n) mn = 1,6749 10-27 1839 me. ( . nucleus ). .
Ze, = 1.6022 10-19 , Z , .
, : , X , Z ( ), ( ).
, . , , , . , , . . , , .
Z, (. . N = Z) , , Z . , (Z=1) : (Z=1, N = 0), (Z= 1, N = 1), (Z= 1, N = 2), , . . ( , , ), , . 2000 , Z, N, .