Question

Explain why is sodium less reactive than potassium?

Answer 1

Hint: By using the concept of the ionization energy (i.e. the energy released when an electron is lost by the atom) and the size of the sodium and the potassium atoms, you can easily explain that potassium is more reactive than the sodium. Now answer it.

Complete answer:
First of all, let’s discuss sodium and potassium first. Both the sodium and magnesium are metals and belong to the s-block elements and both sodium and potassium are alkali metals and magnesium and have the atomic number as 11 and 19 and the mass number as 23 and 39 respectively.
Both Sodium and potassium are very soft and so soft that they could be easily cut with a knife and in its outermost shell it has one electron and has a strong tendency to lose the electron to acquire the stable electronic configuration of the nearest noble gas i.e. the neon. Similarly, magnesium in its outer shell has one electron and has a strong tendency to lose the electrons to acquire the stable electronic configuration of the nearest noble gas i.e. the argon.
Now considering the statement;
Sodium atoms due to being smaller in size have high ionization energy and thus, it can’t lose electrons easily and is more stable and less reactive.
But on the other hand, potassium atoms due to being larger in size than the sodium atom has low ionization energy and thus, they can lose electrons easily and are less stable and more reactive.
Hence, from this it is clear that sodium is less reactive than potassium.

Note:
Ionization energy is the amount of energy released when an atom in gaseous state loses electron to attain the stable electronic configuration in its outermost shell and smaller the size of the atom, larger is its ionization energy and lesser is the ease of the atom to lose the electron and vice-versa.