18 · Ar
Argon
Isolated from air by Rayleigh and Ramsay in 1894.
Identity
- Atomic number
- 18
- Symbol
- Ar
- Canonical name
- Argon
- Category
- noble gas
- Group
- 18
- Period
- 3
- Block
- p
Properties
These quantities come from the Periodic Table JSON compilation. They have not yet been checked, one by one, against CIAAW atomic weights or NIST measurements. A value marked estimated is not a measurement.
- Atomic mass
- 39.9481 u
- Electron configuration
- [Ne] 3s2 3p6
- Electrons per shell
- 2, 8, 8
- Standard state
- gas
- Density
- 1.784 g/L
- Melting point
- 83.81 K
- Boiling point
- 87.302 K
- First ionization energy
- 1,520.6 kJ/mol
- Electron affinity
- -96 kJ/mol
History
Argon from air
Discovery · jointly credited · 1894
Rayleigh and Ramsay isolate an inert constituent of air, distinct from nitrogen.
Etymology
- Theme
- property
- Language
- grec
- Root
- argos
- Meaning
- idle
Scientists
Places and institutions
- London — historical setting : United Kingdom — present country : United Kingdom
See also
Sources
- IUPAC, Periodic Table of the Elements
- Bowserinator, Periodic Table JSON. Compilation secondaire d’où viennent les grandeurs physiques importées (masse, densité, températures, énergies). Elles ne sont pas revérifiées une à une auprès du NIST ou de la CIAAW.
- John Emsley, Nature’s Building Blocks: An A–Z Guide to the Elements