Gold
Definition and meaning of Gold in chemistry.
![Gold element card: symbol Au, atomic number 79, atomic mass 196.97, electron configuration [Xe] 4f¹⁴ 5d¹⁰ 6s¹, oxidation states +3, Transition metal, group 11, period 6, solid at room temperature.](/assets/images/terms/gold-chemical-element.webp)
Gold is a dense, soft transition metal known for its bright yellow color. It has the chemical symbol Au and an atomic number of 79. It is one of the least reactive chemical elements under normal environmental conditions.
In more detail
Gold sits in group 11 and the sixth period of the periodic table. In nature, it mostly occurs in its pure elemental form as nuggets or grains in rocks. Gold is a noble metal, meaning it does not react with oxygen and never rusts.
Most individual acids cannot damage gold, but a strong acid mixture called aqua regia dissolves it easily. Students often think gold is completely unreactive, but it easily forms chemical complexes with cyanide. Gold also has incredible malleability and ductility, which let people shape it with ease.
Malleability means it can be beaten into extremely thin sheets without cracking or breaking. Ductility is the ability of a metal to stretch into a long wire. For instance, a single gram of gold can stretch for over two kilometers.
The most stable oxidation states of gold in chemical compounds are plus 1 and plus 3. These states help form the gold complexes used in high-quality electroplating. Gold is also famous for its yellow color, which is unique among metals.
This yellow color happens because relativistic effects change how inner electrons orbit the heavy nucleus. The fast electrons alter the energy levels, making the metal absorb blue light and reflect yellow light.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Au |
| Atomic number | 79 |
| Atomic mass | 196.97 u |
| Category | Transition-Metal |
| Melting point | 1064 degrees Celsius |
| Crystal structure | Face-centered cubic |
People traditionally use gold to make beautiful jewelry and valuable coins. Today, the electronics industry also uses gold to build reliable computer parts. Gold creates great contact points because it conducts electricity well and never rusts.
Frequently asked questions
Why does gold not tarnish or rust like other metals?
Gold is extremely stable and does not react with oxygen or sulfur in the air. Its outer electrons are held very tightly, so chemical reactions cannot start easily.
What are relativistic effects in gold?
The massive positive charge of the gold nucleus pulls its inner electrons to high speeds. These speeds approach the speed of light and shrink the orbits of the electrons.
Can gold be dissolved by any common household liquids?
No common household liquids can dissolve gold because it is chemically noble and highly stable. Only a mix of concentrated nitric and hydrochloric acids can dissolve it.
Related terms
Sources & references
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