On atom of mg 26 in the ground state has how many valance electrons

Atomic mass is 24.305 so unpaired electrons are 24. I also got 8.. so idk

Because electrons have negligible mass, to account for the mass of the isotope, there must be 16 neutrons, 16 neutrally charged, massive, fundamental particles present in the sulfur nucleus. and thus finally, if we have the 32s2− ion, there are 18 electrons, 16 protons, and 16 neutrons.