Respostas

2014-04-16T09:29:19-03:00
Z=83
A= 209
eletrons, protons e neutrons = ?

A=Z+N
N=a-z
N=209-83
N=126 neutrons

Z= p = e = 83
Assim temos 83 eletrons e 83 protons
2014-04-16T13:21:47-03:00
209 - 83 = N = neutrons
209 = massa
83 = protons 
A = P + N
N = 126