Gold
Gold is a soft yellow metal that resists corrosion and can be worked into very thin layers. Those qualities make it useful in jewellery, reliable electrical contacts, and the mirrors of a space telescope.
A stylized shell model. Electrons are quantum objects, not particles following these literal paths. Sizes and motion are illustrative.
54 is the [Xe] core total across five shells.
At a glance
- Atomic number
- 79
- Atomic mass
- 196.96657 u
- Phase
- Solid
- Density
- 19.3 g/cm³
- Melting point
- 1,337.33 K
- Boiling point
- 3,109 K
- First ionization energy
- 890.1 kJ/mol
- Electronegativity
- 2.54
- Electron affinity
- 222.747 kJ/mol
- Molar heat capacity
- 25.418 J/(mol·K)
- Period
- 6
- Appearance
- metallic yellow
Conditions and isotopes affect measured properties. Some properties of short-lived elements are predicted. Electronegativity uses the Pauling scale.
A golden view of the universe
Webb’s primary mirror uses gold-coated beryllium segments. The gold improves their reflection of infrared light.
Image: NASA / Chris Gunn100 nanometres
The gold coating on each Webb mirror segment is about 100 nanometres thick. The beryllium beneath it supplies the structure; the thin gold surface helps the telescope collect infrared light.
How NASA made Webb’s mirrorsA dependable connection
A contact needs to keep conducting. Gold combines electrical conductivity with resistance to corrosion, making thin coatings useful on electrical connectors. The same softness that allows gold leaf means jewellery often uses harder alloys.
Royal Society of Chemistry · GoldKeep exploring
Explore the stories, imagery, and reference data in more depth. Properties with no value in the reference are marked unavailable.