Answer:
Electrons and protons have opposite electric charge. They are present in the same number, but opposite electric charge. ( since the atom is neutral )
Explanation:
if we look at the periodic table we see, for the sodium atom (Na), that the atomic number (Z) is 11. The atomic number is the number of protons. Protons are positive.
Since this sodium atom is neutral, this means that there are the same number of electrons, which are negative. So also 11 electrons.
Electrons and protons have opposite electric charge.
Following the formula A = Z + N
Here is A = atomic mass, and is the sum of protons ( same as electrons ) + neutrons
As we can see on the periodic table the atomic mass of Sodium(Na) is 23
23 = 11 + N ⇔ N = 23 -11 = 12 neutrons
