Gold
Definition and meaning of Gold in chemistry.
Gold is a chemical element with the symbol Au and atomic number 79, distinguished by its distinctive yellow color, remarkable malleability, and profound historical significance. It is a dense, soft transition metal that ranks among the least reactive chemical elements under standard environmental conditions.
In more detail
Located in group 11 of the sixth period on the periodic table, gold primarily occurs in nature in its native, free elemental form as nuggets or grains in rocks, veins, and alluvial deposits. It is an archetypal noble metal, completely resisting oxidation and corrosion by air or moisture, and remaining impervious to individual acids, though it can be dissolved by the acid mixture aqua regia. Gold possesses unparalleled ductility and malleability; a single gram can be beaten out into a sheet of one square meter or drawn into miles of continuous thin wire. Chemically, its most stable and prevalent oxidation states are +1 and +3, which form various coordination complexes used in electroplating and specialized medical treatments. The metal's unique optical properties, which absorb blue light and reflect red and yellow wavelengths, arise from relativistic effects that alter the energy levels of its orbiting electrons.
Key facts
| Field | General Chemistry |
|---|---|
| Symbol | Au |
| Atomic number | 79 |
| Atomic mass | 196.97 u |
| Category | Transition Metal |
| State at room temperature | Solid |
| Melting point | 1064 degrees Celsius |
| Electrical conductivity | Excellent, trailing only silver and copper |
| Crystal structure | Face-centered cubic |
In addition to its traditional use in jewelry and coinage, gold is extensively employed in the electronics industry to manufacture highly reliable, corrosion-resistant connectors and contact points for computers and telecommunications equipment.
Frequently asked questions
Why does gold not tarnish or rust like other metals?
Gold is incredibly unreactive because its outermost electrons are tightly bound to the nucleus, requiring a substantial amount of energy to participate in chemical reactions with oxygen or sulfur.
What are relativistic effects in gold?
Because of the high positive charge of the gold nucleus, the inner electrons travel at speeds approaching the speed of light, which shrinks their orbitals and ultimately gives gold its distinctive yellow color.