Question

In a different experiment, a student places a piece of pure Ba(s) in a beaker containing 250.mL of 6.44MHCl(aq) and observes that the rate of appearance of H2(g) bubbles when Ba(s) was added is much faster than the rate of appearance of bubbles when the Mg(s) was added. The student claims that the greater reactivity is due to the difference in ionization energy between Mg and Ba. Explain the difference in ionization energy between Mg and Ba in terms of atomic structure.

Answer 1

Answer: The Ionization energy  of Barium is lower and hence it can lose its electrons easily.

Explanation:

Ionization energy is defined as the energy required to remove an electron from an isolated gaseous atom. It is represented as $E_i$

This energy will be higher for fully filled and half-filled electronic configuration than partially filled electronic configuration. This is so because half filled and fully filled configurations are stable.

Magnesium is the 12th element of the periodic table having electronic configuration of = $[Ne]3s^2$

Barium is the 56th element of the periodic table having electronic configuration of $[Xe]6s^2$

Both magnesium and barium belong to the same group as they have similar valence electrons. But as Barium is larger in size, the valence electrons lie farther from the nucleus and lesser energy is required to remove the electron and thus ionization energy will be lower for barium and thus will be more reactive.