L'ion magnésium Mg²⁺ :

• Nucléons = A = Z + N = 12 + 12 = 24 nucléons
• Protons = P = A - N = 24 - 12 = 12 protons
• Electrons = 10
• Neutrons = 12

L'ion sodium Na⁺ :

• Nucléons = 23
• Protons = P = A - N = 23 - 12 = 11 protons
• Electrons = 10
• Neutrons = 12

L'ion soufre S²⁻ :

• Nucléons = 32
• Protons = 16
• Electrons = 18 électrons
• Neutrons = N = A - Z = 32 - 16 = 16 neutrons

L'ion brome Br⁻ :

• Nucléons = A = Z + N = 35 + 45 = 80 nucléons
• Protons = 35
• Electrons = 36
• Neutrons = 45