The atomic size of sodium is bigger than atomic size of Magnesium.

Question

Give scientific reasons:

The atomic size of sodium is bigger than atomic size of Magnesium.

Answer 1

• The atomic size of an element depends on the number of electron orbits in the atom of that element. 
• If 2 atoms have the same outermost orbit, then the atom having the larger number of electrons in the outermost orbit is smaller than the one having fewer electrons in the same outermost orbit. 
• Atomic number of sodium (Na) is 11. Hence, its electronic configuration is (2, 8, 1) while atomic number of magnesum (Mg) is 12 and hence its electronic configuration is (2, 8, 2). 
• As compared to sodium atom Magnesum atom has larger number of electrons n its electronic configuration.
• Therefore, atomic size of sodium is bigger than atomic size of Magnesium.