Why Is Mercury a Liquid

The silver liquid called mercury has been known since ancient times. In fact the symbol for mercury (Hg) comes from its Greek name Hydrargyrum, which means watery silver. Although elements in the liquid state at ambient temperature and pressure are quite rare (Br2 is another example), the liquid nature of mercury is especially confounding. For example, compare the properties of mercury and gold  

It is quite apparent that these metals, which are neighbors on the periodic table, have strikingly different properties. Why The answer is not at all straightforward—but very interesting. It seems to hinge on relativity. 

Recall that Einstein postulated in his theory of special relativity in 1905 that the mass (m) of a moving object increases with its velocity (v)  

Liquid mercury forms flat drops because of its lack of surface tension. 

It turns out that relativity has an even more profound impact on atomic theory than the above calculations suggest. A relativistic treatment of the atom fundamentally changes the way we view the electrons in atoms. In fact, as shown by British physicist Paul Dirac, the concept of electron spin occurs naturally in a relativistic treatment of the 

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