18
Ar
Argon
39.9481
Basic Information
Name
Argon
Atomic Number
18
Gas Phase
Monatomic
Appearance
Colorless gas glows lilac-purple when placed in a high-voltage electric field
Refractive Index
1.000281
Phase At STP
Gas
Spectrum Image
Source
WikipediaBohr Model
Static
Interactive
Descriptive Numbers
CAS Number
7440-37-1
CID Number
CID23968
DOT Number
1951
RTECS Number
RTECSCF2300000
Mendeleev Number
114
Pettifor Number
3
Space Group Number
225
Glawe Number
3
Mass
Atomic Mass
39.9481 Da
Uncertainty
0.001
Periodic Position
X Position
18
Y Position
3
Period
3
Group
18
Classification
Block
p
Category
Noble Gas
Geochemical
Volatile
Goldschmidt
Atmospheric
Abundance
Seawater
4.5e-7 kg/L
Sun
0.1 mole ratio to silicon
Earth Crust
0.0000035 g
Solar System
0.1 mole ratio to silicon
Meteorites
N/A %
Color
Jmol
#80D1E3
Molcas Gv
#80D1E3
CPK
#FF1493
Atomic Radius
Empirical
71
Calculated
71
Van Der Waals
188
Bonding
188
Rahm
197
Uff
386.8
Mm3
199
Alvarez
194
Covalent (Single Bound)
97
Covalent (Triple Bound)
96
Covalent (Cordero)
106
Covalent (Pyykko)
96
Covalent (Pyykko Double)
107
Covalent (Pyykko Triple)
96
Temperature
Melting/Freeze (USE)
83.81 °K
Melting/Freeze (WEL)
83.8 °K
Melting/Freeze (CRC)
83.66 °K
Melting/Freeze (LNG)
83.62 °K
Boiling/Density (USE)
87.302 °K
Boiling/Density (WEL)
87.3 °K
Boiling/Density (CRC)
87.152 °K
Boiling/Density (LNG)
87.13 °K
Boiling/Density (Zhang)
87 °K
Critical Temperature
150.87 °K
Critical Pressure
4.898 MPa
Density
STP
1.784 kg/cm³
Gas
1.784 kg/cm³
Heat
Molar Volume
22.56 cm³/mol
Atomic Volume
24.2 cm³
Heat Of Fusion CRC
1.18 kJ/mol
Heat Of Fusion LNG
1.12 kJ/mol
Heat Of Fusion WEL
1.18 kJ/mol
Evaporation USE
6.52 kJ/mol
Evaporation CRC
6.43 kJ/mol
Evaporation LNG
6.43 kJ/mol
Evaporation WEL
6.5 kJ/mol
Evaporation Zhang
6.53 kJ/mol
Heat Capacity USE
0.138 J/gK
Heat Capacity CRC
20.786 J/gK
Heat Capacity LNG
20.79 J/gK
Heat Capacity WEL
20.786 J/gK
Thermal Conductivity
0.0177 W/m*K
Adiabatic Index
42799
Speed of Sound
Fluid
323 m/s
Magnetic Properties
Order
Diamagnetic
Susceptibility
-6e-9 m3/kg
Etymology
Description
It is a monatomic noble gas. It makes up 0.93% of the air. It is colorless and odorless. It is inert and has no real compound. Lord Rayleigh and Sir William Ramsey discovered it in 1894
Language Of Origin
Greek
Origin Of Word
From the Greek word argos, meaning "idle (standing)"
Meaning
inactive, inactive
Symbol Origin
descriptor: argon
Etymological Description
In Greek, argon means "inactive", "without effect" (literally "slow").
Discovery & Isolation
Observed/Predicted By
Lord Rayleigh ve W. Ramsay
Observed/Discovery Year
1894
Discovery Location
Isolated Sample By
Lord Rayleigh ve W. Ramsay
Isolated Sample Year
1894
Production & Use
Sources
It is continuously released into the air by the decay of radioactive potassium-40. Its pure form is obtained by fractional distillation of liquid air.
Uses
It is used in lighting products. It is an element frequently used in the filling of incandescent bulbs. A certain amount of it is mixed with krypton in fluorescent lamps. Crystals in the semiconductor industry are obtained in argon atmospheres.
Radioactivity
Half Life
Stable
Lifetime
Stable
Neutron Mass Absorption
0.0006
Neutron Cross Section
0.65
Electron Affinity
Proton Affinity
369.2
Electron Affinity (eV)
-11.5
Electron Affinity (kJ/mol)
-96
Electron Affinity (allen)
19.17
Electron Affinity (ghosh)
0.2922
Dipole Polarity
Accepted
11.083
Uncertainty
0.007
C6 GB
67.4
C6 Coefficient
64.2
Lattice
Constant Internal Default Radius
5.26
Constant
525.6, 525.6, 525.6
Strucutre
FCC
Angles
p/2, p/2, p/2
Electron & Quantum
Electron Configuration
1s2 2s2 2p6 3s2 3p6
Quantum Number
1S0
Electron Configuration Semantic
[n] stick
Shells-0
2
Shells-1
8
Shells-2
8
Ionization Energies-0
1520.6
Ionization Energies-1
2665.8
Ionization Energies-2
3931
Ionization Energies-3
5771
Ionization Energies-4
7238
Ionization Energies-5
8781
Ionization Energies-6
11995
Ionization Energies-7
13842
Ionization Energies-8
40760
Ionization Energies-9
46186
Ionization Energies-10
52002
Ionization Energies-11
59653
Ionization Energies-12
66199
Ionization Energies-13
72918
Ionization Energies-14
82473
Ionization Energies-15
88576
Ionization Energies-16
397605
Ionization Energies-17
427066
