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Argon (Ar)
Atomic number: 18 · Category: noble gas · Group 18 · Period 3 · Phase: Gas
Argon is a chemical element with symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most common gas in the Earth's atmosphere, at 0.934% (9,340 ppmv), making it over twice as abundant as the next most common atmospheric gas, water vapor (which averages about 4000 ppmv, but varies greatly), and 23 times as abundant as the next most common non-condensing atmospheric gas, carbon dioxide (400 ppmv), and more than 500 times as abundant as the next most common noble gas, neon (18 ppmv).
Atomic mass: 39.9481
Density: 1.784
Melting point: 83.81 K
Boiling point: 87.302 K
Appearance: colorless gas exhibiting a lilac/violet glow when placed in a high voltage electric field
Source: Wikipedia
Block: p
CPK color:#80d1e3
Electronic structure
Electron configuration: 1s2 2s2 2p6 3s2 3p6
Configuration (semantic): [Ne] 3s2 3p6
Shells: 2, 8, 8
Electron affinity: -96
Ionization energies: 1520.6, 2665.8, 3931, 5771, 7238, 8781, 11995, 13842, 40760, 46186, 52002, 59653, 66199, 72918, 82473, 88576, 397605, 427066
Periodic position
Group: 18
Period: 3
xpos: 18
ypos: 3
Spectral/Bohr images
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3D Model