
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
- 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.
- Most of the Earth’s gold came from meteor bombardments occurring around 200 million years after the planet formed.
- 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.
- 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.”
- 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.
- 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.
- 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.
- 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.
- Like other noble metals, the low reactivity of pure gold makes it odorless and flavorless.
- Gold is a precious metal. The precious metals are rare, beautiful metals. Their low reactivity and value makes them useful for coins and jewelry.
- 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.
- “Pure” gold still contains trace impurities. Gold bars at Fort Knox are 24-karat gold, with a purity of 99.95%.
- 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.
- Gold, in the form of gold chloride, turns glass ruby red.
- 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