Respuesta :

The atomic number of an element is equal to the number of protons. It the element has a neutral charge then the number of protons equals the number of electrons. The number of neutrons equals the atomic mass minus the atomic number.

ex:
Sodium
Atomic number:  11 
Atomic mass: 23 

Protons: 11
Electrons: 11
Neutrons: 23 - 11 = 12
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