Chemical and Physical Properties of Gold

Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels.

Gold, an element known to ancient man, has always been prized for its color. It was used as jewelry in prehistoric times, alchemists spent their lives trying to transmute other metals into it, and it's still one of the most prized metals.

Below, discover some basic facts about gold, its common uses, information on where it's found, and a bit of fun gold trivia.

Gold Basics

• Atomic Number: 79
• Symbol: Au
• Atomic Weight: 196.9665
• Discovery: known since prehistoric time
• Electron Configuration: [Xe]6s 1 4f 14 5d 10
• Word Origin: Sanskrit Jval; Anglo-Saxon gold; meaning gold - also Latin aurum, shining dawn
• Isotopes: There are 36 known isotopes of gold ranging from Au-170 to Au-205. There's only one stable isotope of gold: Au-197. Gold-198, with a half-life of 2.7 days, has been used to treat cancer and other illnesses.

Gold Physical Data

• Density (g/cc): 19.3
• Melting Point (°K): 1337.58
• Boiling Point (°K): 3080
• Appearance: 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 exist but 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

Properties

In mass, gold is a yellow-colored metal, although it may be black, ruby, or purple when finely divided. Gold is a good electricity and heat conductor. It's not affected by exposure to air or most reagents. Gold is inert and a good reflector of infrared radiation. It's usually alloyed to increase its strength. Pure gold is measured in troy weight, but when gold is alloyed with other metals, the term karat is used to express the amount of gold present.

Common Uses for Gold

Gold is used in coinage and is the standard for many monetary systems. You'll find gold in jewelry, dental work, plating, and reflectors. Chlorauric acid (HAuCl₄) is used in photography to tone silver images. Disodium aurothiomalate, administered intramuscularly, is a treatment for arthritis.

Where Gold Is Found

Gold is found as a free metal and in tellurides. It's widely distributed and almost always associated with pyrite or quartz. Gold is found in veins and alluvial deposits. It occurs in seawater in the amount of 0.1 to 2 mg/ton, depending on the location of the sample.

Gold Trivia

• Gold is one of the few elements found in its native state.
• Gold is the most malleable and ductile metal. One ounce of gold can be beaten to 300 ft 2 or stretched into a wire 2000 kilometers long (1 μm thick).
• Gold's melting point is an assigned value, which serves as a calibration point for the International Temperature Scale and International Practical Temperature Scale.
• The gold ion in the +1 oxidation state (Au(I) + ) is called the aurous ion.
• The gold ion in the +3 oxidation state (Au(III) 3+ ) is called the auric ion.
• Compounds containing gold in the -1 oxidation state are called aurides (cesium and rubidium can form auride compounds).
• Gold is one of the noble metals. Noble metal is an alchemical term for metals that don't corrode under normal conditions.
• Gold is the seventh most dense metal.
• Metallic gold has no odor or taste.
• Gold has been used as jewelry since prehistoric times. Today, gold in jewelry isn't pure gold. Jewelry gold is made of many different gold alloys.
• Gold is resistant to most acids. The acid aqua regia is used to dissolve gold.
• Elemental gold metal is considered non-toxic and occasionally used as a food additive.
• Transmuting lead into gold was one of the major goals of the alchemists. Modern nuclear chemists have found methods to accomplish this historic task.​

References

Los Alamos National Laboratory (2001), Crescent Chemical Company (2001), Lange's Handbook of Chemistry (1952) International Atomic Energy Agency ENSDF database (Oct 2010)

Helmenstine, Anne Marie, Ph.D. "Chemical and Physical Properties of Gold." ThoughtCo, Sep. 1, 2024, thoughtco.com/gold-facts-606539. Helmenstine, Anne Marie, Ph.D. (2024, September 1). Chemical and Physical Properties of Gold. Retrieved from https://www.thoughtco.com/gold-facts-606539 Helmenstine, Anne Marie, Ph.D. "Chemical and Physical Properties of Gold." ThoughtCo. https://www.thoughtco.com/gold-facts-606539 (accessed September 8, 2024).

• About Us
• Advertise
• Careers
• Privacy Policy
• Editorial Guidelines
• Contact
• Terms of Service
• EU Privacy

We Care About Your Privacy

We and our 100 partners store and/or access information on a device, such as unique IDs in cookies to process personal data. You may accept or manage your choices by clicking below, including your right to object where legitimate interest is used, or at any time in the privacy policy page. These choices will be signaled to our partners and will not affect browsing data.

We and our partners process data to provide:

Store and/or access information on a device. Use limited data to select advertising. Create profiles for personalised advertising. Use profiles to select personalised advertising. Create profiles to personalise content. Use profiles to select personalised content. Measure advertising performance. Measure content performance. Understand audiences through statistics or combinations of data from different sources. Develop and improve services. Use limited data to select content. List of Partners (vendors)