Interesting Gold Facts

This entry was posted on by (updated on )
Gold Facts
Gold is the only metal with a yellowish or “golden” color.

There are many interesting gold facts. Gold is the only yellow-colored metal on the periodic table, where it has symbol Au and atomic number 79. These facts include its properties, uses, and sources.

Interesting Gold Facts

  1. Gold is the only truly “golden” metal on the periodic table. Certain nonmetals are yellow, including sulfur and chlorine. Other metals appear golden, but only when they are oxidized.
  2. Most of the Earth’s gold came from meteor bombardments occurring around 200 million years after the planet formed.
  3. Gold is one of a handful of elements known since ancient times because it occurs in pure form naturally. Prehistoric humans also knew carbon, iron, copper, sulfur, zinc, silver, and mercury.
  4. The element symbol Au comes from the old Latin name for gold, aurum, which means “shining dawn” or “sunrise glow.” The modern word gold is a Germanic word meaning “yellowish green.”
  5. Gold is highly ductile. One ounce (about 28 grams) stretches into a fine wire 5 miles (8 kilometers) long. The flexible wires can even be used thread in sewing.
  6. Gold is the most malleable element, which means it’s easy to pound it into thin sheets. One ounce of gold is so malleable it can form a 300-square-foot sheet that is so thin that it’s transparent. Thin gold sheets appear greenish-blue rather than gold because the element reflects red and yellow light.
  7. Gold is very heavy and dense, but it isn’t considered a heavy metal because it’s generally nontoxic. You can eat gold flakes or use them in drinks. But, some people are allergic to gold.
  8. Gold is a noble metal. Noble metals resist corrosion and chemical attack. Most metals dissolve in common acids, but you need aqua regia to dissolve gold.
  9. Like other noble metals, the low reactivity of pure gold makes it odorless and flavorless.
  10. Gold is a precious metal. The precious metals are rare, beautiful metals. Their low reactivity and value makes them useful for coins and jewelry.
  11. A karat of gold is 1/24th of a portion of pure gold. The word karat comes from carob seeds, which were used in ancient bazaars to measure the weight of gold. Pure gold is 24 karats, while 18-karat gold is 75% gold, 14-karat gold is 58.5% gold, and 10-karat gold is 41.7% gold. Most gold is 14k or 10k because high-purity gold is soft and easily scratched and deformed. The remaining percentage of metal in karat gold usually is silver, but can be copper, platinum, nickel, iron, or cadmium.
  12. “Pure” gold still contains trace impurities. Gold bars at Fort Knox are 24-karat gold, with a purity of 99.95%.
  13. Gold has many uses. Of course, it’s used for jewelry, currency, and as a status symbol. But, its desirable properties also make it important in electronics, wiring, radiation shielding, and medicine. About 50% of gold finds use in jewelry, 40% in investments, and 10% in industry.
  14. Gold, in the form of gold chloride, turns glass ruby red.
  15. Gold comes from China, Australia, Russia, the United States, Canada, Peru, and South Africa.

Gold Facts – Chemical and Physical Properties

  • Atomic Number: 79
  • Symbol: Au
  • Atomic Weight: 196.9665
  • Discovery: Gold has been known since prehistoric time.
  • Electron Configuration: [Xe]6s14f145d10
  • Name Origin: Sanskrit Jval; Anglo-Saxon gold; meaning gold – also Latin aurum, shining dawn
  • State of Matter: Solid
  • Isotopes: There are 36 known isotopes of gold ranging from Au-170 to Au-205. There is only one stable isotope of gold: Au-197. Gold-198 has a half-life of 2.7 days and finds use treating cancer and other illnesses.
  • Density (g/cc): 19.3
  • Melting Point (°K): 1337.58
  • Boiling Point (°K): 3080
  • Appearance: Gold is a soft, malleable, yellow metal.
  • Atomic Radius (pm): 146
  • Atomic Volume (cc/mol): 10.2
  • Covalent Radius (pm): 134
  • Ionic Radius: 85 (+3e) 137 (+1e)
  • Specific Heat (@20°C J/g mol): 0.129
  • Fusion Heat (kJ/mol): 12.68
  • Evaporation Heat (kJ/mol): ~340
  • Debye Temperature (°K): 170.00
  • Pauling Negativity Number: 2.54
  • First Ionizing Energy (kJ/mol): 889.3
  • Oxidation States: +3, +1. The oxidation states -1, +2 and +5 are rare.
  • Lattice Structure: Face-Centered Cubic (FCC)
  • Lattice Constant (Å): 4.080
  • Specific Gravity (20°C): 18.88
  • CAS Registry Number: 7440-57-5

References

  • Chen, Jennifer; Lampel, Heather (2015). “Gold Contact Allergy: Clues and Controversies.” Dermatitis 26(2): 69-77. doi:10.1097/DER.0000000000000101
  • Kelly, P. F. (2015). Properties of Materials. CRC Press. ISBN 978-1-4822-0624-1.
  • Möller, Halvor (2010). “Contact allergy to gold as a model for clinical-experimental research.” Contact Dermatitis 62(4): 193-200. doi:10.1111/j.1600-0536.2010.01671.x
  • Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. ISBN 0-8493-0464-4.
  • Willbold, Matthias; Elliott, Tim; Moorbath, Stephen (2011). “The tungsten isotopic composition of the Earth’s mantle before the terminal bombardment”. Nature. 477 (7363): 195–8. doi:10.1038/nature10399