Question

In 3d-series, which one has the minimum melting point?
(a)- V
(b)- Mn
(c)- Zn
(d)- Cu

Answer 1

Hint: The melting point of the d-block elements is due to the presence of unpaired electrons in the last d-orbital or s-orbital. So, the element which has all the electrons in pairs will have the least melting point.

Complete step by step answer:
The 3d series elements come under d-block elements which are also known as transition metals.
The transition metals have a very high melting point and boiling points. As the atomic number in series of the transition metal the melting points increase and then suddenly decrease. Since the transition metals are heavy metals so they form strong metallic bonds which make the melting and boiling points very high. The strong metallic bonds are due to the presence of unpaired electrons in the d-orbital and s-orbital. Hence they have high enthalpies of atomization. But the last element of the series has the least melting point because it has fully filled orbitals So, in:
(a)- V: It is vanadium and its atomic number is 23. The electronic configuration of vanadium is $[Ar]3d^{3}4s^2$. So it has 3 unpaired electrons.

(b)- Mn- It is manganese and its atomic number is 25. The electronic configuration of manganese is $[Ar]3d^{5}4s^2$ . So it has 5 unpaired electrons.

(c)- Zn: It is zinc and its atomic number is 30. The electronic configuration of zinc is $[Ar]3d^{10}4s^2$ . So it has 0 unpaired electrons.

(d)- Cu: It is copper and its atomic number is 29. The electronic configuration of copper is $[Ar]3d^{10}4s^1$ . So it has 1 unpaired electron.
So, the zinc has 0 unpaired electrons hence it will have the least melting point.
So, the correct answer is “Option C”.

Note: In the 3d-series the Zinc has the least melting point, similarly, the Cadmium in the 4d-series and Mercury in the 5d-series has the least melting point because they have all electrons in pairs.