Question

Why is mercury Liquid at room temperature?
A.They have a boiling point
B.They have high intermolecular forces
C.Valence electrons are not shared easily
D.None of the above

Answer 1

Hint: Mercury is the only metal which remains in liquid form at room temperature and pressure.
-It has a symbol of Hg and an atomic number of 80.
-Mercury is commonly known as quicksilver and has a melting point of $-{38.83}^{o}C$.
-The electronic configuration of mercury is $\text{[Xe]4}{\text{f}}^{\text{14}}\text{5}{\text{d}}^{\text{10}}\text{6}{\text{s}}^{\text{2}}$.

Complete step by step answer:
Let us look into the reason for this unexpected property of mercury:
As stated in the question mercury is the only metal which is liquid at room temperature. It is because mercury is very bad at sharing its valence electrons.
Most of the metals are hard and have a high melting point. This is because they readily share their valence electrons with the neighbouring atom.
But when it comes to mercury electrons in mercury are bound more tightly than usual to the nucleus of the atom and thus are not free to move and thus not shared. This unusual property of mercury is due to the filled valence shell of mercury which gives it the extra stability.
As you can see in the electronic configuration of the mercury given above all the orbitals are filled. And as we all know filled orbitals are highly stable thus valence electrons are not shared easily when it comes to mercury.
Hence, option C is the correct answer.

Note:Mercury is used in thermometers due to its unusual property of being in a liquid state at room temperature and its high coefficient of expansion due to which even the slightest temperature change is noticeable.