Specify the number of protons, neutrons, and electrons in the neutral atom copper-64.
Number of protons - 29 Number of electrons - 29 Number of neutrons - 35
The number of protons is equal to the atomic number ( for copper it's 29) The number of electrons is equal to the number of protons, because the atom is neutral (for copper it's 29) The atomic weight is the total number of protons and neutrons. For copper it's 64. That's why the number of neutrons is 64 - 29 = 35