Question

The most reactive metal is?
(A) Sodium
(B) Magnesium
(C) Potassium
(D) Calcium

Answer 1

Hint: We can say that in metals, as we go from right to left in the periodic table, reactivity increases. As we go from up to down in the periodic table, reactivity of metals increases.


Complete step by step answer:
Let us understand the reactivity of metals in the periodic table.
- As we know the chemical reactivity decreases as you go left to right of the periodic table and it increases as you go down the group in the case of metals.
- This happens because as you go down the group, it is easier for electrons to be taken away, which results in high chemical reactivity and as you go from left to right the elements in the periodic table have more electrons in their valence shells, so they are not as reactive in compared to the metals which have less valency.
- As we have already discussed, reactivity of alkali metals tends to increase as you go down the group. Therefore, sodium is less reactive with water than is potassium, likewise with the alkaline metals; calcium is more reactive than magnesium. Also, as the extreme left elements have higher radius and lowest ionization energy, which results in high reactivity.
- Therefore, out of the above elements, potassium is present at the extreme left of periodic and also at the lowest position down the group amongst the given elements in the options.
- Potassium metal has more number of shells compared to sodium and thus it becomes easy to remove one electron from its outermost orbital ( less ionization enthalpy).
- So, out of given metals, Potassium is the most reactive metal.


Therefore, potassium is the most reactive metal among the given options. Hence, option C is the required answer.



Note: Remember that in case of metals, reactivity depends upon the ease of removal of the valence electrons. We can say that a more reactive metal will displace a less reactive metal from its solution.