Mercury (Hg)

General Information

• Symbol: Hg
• Atomic Number: 80
• Atomic Weight: 200.592 u
• Element Category: Transition metal
• Group: 12
• Period: 6
• Block: d-block

Physical Properties

• Appearance: Silvery-white metallic liquid
• Density: 13.534 g/cm³ at 20°C
• Melting Point: -38.83 °C (-37.89 °F)
• Boiling Point: 356.73 °C (674.11 °F)
• Phase at STP: Liquid
• Electron Configuration: [Xe] 4f¹⁴ 5d¹⁰ 6s²
• Oxidation States: +2 (most common), +1

Chemical Properties

• Reactivity: Mercury is relatively inert and does not react with most acids (except oxidizing acids like nitric acid) or bases. It forms amalgams with many metals, such as gold and silver.
• Compounds: Forms compounds such as mercuric chloride (HgCl₂), mercurous chloride (Hg₂Cl₂), and methylmercury (CH₃Hg).

Uses and Applications

• Thermometers and Barometers: Traditionally used in thermometers, barometers, and other scientific instruments due to its liquid state at room temperature and high density.
• Electrical Switches and Relays: Used in electrical switches, relays, and other devices where its liquid form and conductivity are advantageous.
• Dental Amalgams: Used in dental amalgams for fillings, although its use is decreasing due to health concerns.
• Lighting: Employed in fluorescent and mercury-vapor lamps.
• Gold Mining: Used in artisanal and small-scale gold mining to extract gold from ore by forming an amalgam.

Occurrence and Extraction

• Natural Occurrence: Found mainly in the mineral cinnabar (HgS). It also occurs in small quantities in some other minerals and as a free element in the Earth’s crust.
• Extraction: Extracted primarily by heating cinnabar in the presence of oxygen, which decomposes the ore and releases mercury vapor that is then condensed.

Isotopes

• Stable Isotopes: Mercury has seven stable isotopes, including Mercury-196, Mercury-198, Mercury-199, Mercury-200, Mercury-201, Mercury-202, and Mercury-204.
• Radioactive Isotopes: Several radioactive isotopes, including Mercury-194, Mercury-195, and Mercury-203, used in scientific research and medical applications.

Safety and Handling

• Hazards: Mercury and its compounds are highly toxic and can cause serious health issues, including neurological damage. Methylmercury is particularly dangerous as it bioaccumulates in the food chain.
• Precautions: Handle with extreme care using appropriate protective equipment. Avoid inhalation of vapors, ingestion, and skin contact. Mercury spills should be cleaned up immediately using specific procedures to prevent contamination.

History

• Discovery: Known to ancient civilizations. The earliest known use dates back to ancient Egypt and China.
• Name Origin: The name “mercury” comes from the Roman god Mercury, known for his speed and mobility. Its symbol “Hg” is derived from the Greek word “hydrargyrum,” meaning water-silver.

Additional Facts

• Crystal Structure: Rhombohedral when solid
• Magnetic Properties: Diamagnetic
• Thermal Conductivity: Low, about 8.3 W/m·K
• Electrical Resistivity: High, about 961 nΩ·m at 0 °C

Summary

Mercury is a unique transition metal known for being the only metal that is liquid at room temperature. It has significant applications in scientific instruments, electrical devices, lighting, and historically in dental amalgams and gold mining. Found primarily in cinnabar, mercury is extracted through roasting. Due to its high toxicity, mercury requires careful handling and specific precautions to avoid environmental contamination and health risks.

40 Question and Answer Pairs About Mercury

1. What is the atomic number of Mercury?

   • 80

2. What is the symbol for Mercury?

   • Hg

3. What is the atomic weight of Mercury?

   • 200.592 u

4. In which group of the periodic table is Mercury found?

   • Group 12

5. What period is Mercury in?

   • Period 6

6. What block does Mercury belong to?

   • d-block

7. What is the melting point of Mercury?

   • -38.83 °C (-37.89 °F)

8. What is the boiling point of Mercury?

   • 356.73 °C (674.11 °F)

9. What is the density of Mercury at 20°C?

   • 13.534 g/cm³

10. What is the electron configuration of Mercury?

    • [Xe] 4f¹⁴ 5d¹⁰ 6s²

11. What are the common oxidation states of Mercury?

    • +2, +1

12. What is the appearance of Mercury?

    • Silvery-white metallic liquid

13. Is Mercury reactive with air?

    • Mercury is relatively inert and does not react with most acids or bases.

14. Name a compound of Mercury.

    • Mercuric chloride (HgCl₂)

15. What is a common use of Mercury in thermometers?

    • Used due to its liquid state at room temperature and high density.

16. How is Mercury used in electrical devices?

    • Used in switches and relays for its liquid form and conductivity.

17. What role does Mercury play in dentistry?

    • Used in dental amalgams for fillings.

18. How is Mercury used in lighting?

    • Employed in fluorescent and mercury-vapor lamps.

19. What application does Mercury have in gold mining?

    • Used to extract gold from ore by forming an amalgam.

20. Name a mineral that contains Mercury.

    • Cinnabar (HgS)

21. How is Mercury extracted from ores?

    • By heating cinnabar in the presence of oxygen to release mercury vapor.

22. What is the most stable isotope of Mercury?

    • Mercury-202

23. Name a radioactive isotope of Mercury used in research.

    • Mercury-203

24. What safety hazard is associated with Mercury compounds?

    • Highly toxic and can cause neurological damage.

25. Where does the name Mercury come from?

    • From the Roman god Mercury, symbolized by speed and mobility.

26. What is the crystal structure of solid Mercury?

    • Rhombohedral

27. Is Mercury paramagnetic or diamagnetic?

    • Diamagnetic

28. What is the thermal conductivity of Mercury?

    • About 8.3 W/m·K

29. What is the electrical resistivity of Mercury at 0 °C?

    • About 961 nΩ·m

30. What is the primary oxidation state of Mercury?

    • +2

31. Is Mercury found as a free element in nature?

    • Rarely, it is mostly found in cinnabar.

32. What is the common name of mercurous chloride?

    • Calomel (Hg₂Cl₂)

33. What is a major application of methylmercury (CH₃Hg)?

    • It is a dangerous environmental pollutant.

34. How does Mercury benefit thermometers?

    • Its liquid state over a wide temperature range makes it ideal for precise temperature measurements.

35. What is the boiling point of Mercury in Kelvin?

    • 629.88 K

36. What group does Mercury belong to in the periodic table?

    • Transition metals

37. What is the natural abundance of Mercury-202?

    • About 29.86%

38. Can Mercury be used in high-temperature applications?

    • Yes, in certain scientific instruments.

39. What is the key property that makes Mercury valuable in electrical switches?

    • Its liquid form and conductivity.

40. What precaution should be taken when handling Mercury spills?

    • Clean up immediately using specific procedures to prevent contamination.