Mercury is called quicksilver. It is a heavy, silver-white metallic element that is liquid at room temperature. It is the only metal that is liquid at ordinary temperatures and pressures. Here is a detailed explanation of why mercury is called quicksilver.

Properties of Mercury:
- Mercury is a chemical element with the symbol Hg and atomic number 80.
- It has a melting point of -38.83 degrees Celsius (-37.89 degrees Fahrenheit) and a boiling point of 356.73 degrees Celsius (674.11 degrees Fahrenheit).
- It has a high density and is around 13.5 times denser than water.
- Mercury is a poor conductor of heat, but a good conductor of electricity.
- It has a unique property known as a low surface tension, which allows it to form small, round droplets on surfaces.
- Mercury is highly toxic and can cause serious health problems if ingested or inhaled.

Origin of the Name "Quicksilver":
- The term "quicksilver" is a combination of two words: "quick" and "silver".
- The word "quick" in this context refers to the old English usage meaning "alive" or "lively" and is used to describe the liquid and flowing nature of mercury.
- The word "silver" is a reference to its silver-white color and metallic properties.

Reasons for Calling Mercury "Quicksilver":
1. Liquid State:
- Mercury is the only metal that is liquid at room temperature.
- This unique property of mercury, being in a liquid state, gives it a quick and flowing appearance similar to that of a silver-colored liquid.

2. High Mobility:
- Mercury has a low viscosity, which means it flows easily.
- Its low surface tension allows it to form small droplets and quickly move across surfaces.
- This mobility and quick movement of mercury gave rise to the term "quicksilver".

3. Reflective Nature:
- Mercury has a shiny, silver-white color similar to that of silver.
- Its reflective properties make it resemble the metal silver, further justifying the term "quicksilver".

Conclusion:
Mercury is called quicksilver due to its unique properties of being a liquid metal at room temperature, its high mobility and quick flow, and its reflective silver-white appearance. The combination of the words "quick" and "silver" accurately describes the lively and flowing nature of this element.