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Gold (Au), element 79
Gold (Au) is the chemical element with atomic number 79: a transition metal in group 11, period 6. At 25 °C it is a solid, with an atomic mass of 197 u.
Physical and chemical data
| Atomic number | 79 |
|---|---|
| Symbol | Au |
| Atomic mass | 197 u |
| Density | 19.28 g/cm³ |
| Melting point | 1,064.18 °C (1,337.33 K) |
| Boiling point | 2,855.85 °C (3,129 K) |
| Electronegativity (Pauling) | 2.54 |
| Electron configuration | [Xe]6s1 4f14 5d10 |
| Atomic radius (van der Waals) | 166 pm |
| Oxidation states | +3, +1 |
| Physical state at 25 °C | solid |
| Family | transition metal |
| Group and period | 11 / 6 |
| Discoverer and year | known since antiquity |
Humanity has lived with gold since before chemistry existed as a science: there is no discoverer to record, only millennia of use.
Neighbours on the table
Horizontally, one proton less lands on Platinum (Z=78); one more lands on Mercury (Z=80). Vertically, group 11 gathers relatives with similar behaviour: Copper, Silver, Roentgenium.
The story behind the name
The symbol Au comes from the Latin aurum, tied to aurora and shine. It is the quintessential metal of antiquity: it does not rust or tarnish, which is why it crosses millennia intact, from Egyptian funeral masks to the plated contacts in your phone. All the gold ever mined by humanity would fit in a cube roughly 22 metres on a side, shorter than a tennis court is long. And its cosmic origin is worthy of the price tag: Earth's gold was forged in extreme events such as neutron star collisions, billions of years before becoming a wedding ring.
Physical and chemical data: PubChem Periodic Table (NCBI, compiling NIST and IUPAC), public domain, snapshot of 2026-07-10. Temperatures converted from kelvin; historical notes cross checked against classic chemistry references.
Last updated: · Methodology and sources