A sodium atom and ion, differ by one electron. Sodium loses one electron to form sodium ion.

for 100 moles, each of sodium atoms and ions there would be a difference of 100 moles of electrons. Thus, the mass of 100 moles of electrons = 5.48002 g

As 1 mole of electron have 6.022 × 10²³ electrons

Therefore, mass of 6.022 × 10²³electrons =

Mass of one electron = = 9.1 ×10^-28 g