Question

Which metal has a high melting point?
(A) Sn
(B) W
(C) Sb
(D) Pb

Answer 1

Hint: The metal is a d-block element. The metal has similar properties as chromium and molybdenum. The metal is a d-block element. The metal has similar properties as chromium and molybdenum. Check the options and see which one of them matches these criterias. You will get the answer.

Complete step by step answer:
Melting of a substance is referred to the change in phase of the substance from solid to liquid state. Thus this is a phase change phenomenon.
As we have seen that during melting a solid is transformed to liquid we will further look at the bonding in solid and liquid. Solids are packed in crystal lattice with strong intermolecular forces of attraction. When heat is passed, the heat energy overcomes the internal binding energy of crystal lattice. This results in the weakening of intermolecular forces of attraction. Due to this weakening of force the stability of the crystal lattice gets disturbed because of which molecules separate out from each other and move in random directions. This is the point where melting of a substance is initiated.

The temperature of a solid at which solid gets converted to liquid at atmospheric pressure is said to be melting point. At melting point, solid and liquid phases stay in equilibrium which means that at this point there is existence of both solid and liquid states.

The metal Tungsten has the highest melting point. The melting point is ${3422}^{\circ }C$. Tungsten is also known as wolfram. The abbreviation is W. This element belongs to group 6 of the periodic table. The element has the atomic number of 74. It is a polyvalent metallic element which resembles chromium and molybdenum in many of its properties. Tungsten is used especially in carbide materials as well as in electrical components.

The metal melts when the vibrational lattice modes are over excited with respect to electron cohesive energy. The electronic configuration of tungsten is $[Xe]6s^{1}4f^{14}5d^5$. The stability of a degenerate half-filled d shell causes the atomic radius to shrink thus increasing the density. This also causes delocalization of free electrons more efficiently. Thus the increase in the shielding is much more as compared to other metals. Thus tungsten has the highest melting point.
So, the correct answer is “Option C”.

Note: Generally metals are hard but there are exceptions that are sodium and potassium that are soft in nature. As tungsten has the highest melting point, it is used in incandescent bulbs.