Noble gas

  • noble gases
    hydrogen helium
    lithium beryllium boron carbon nitrogen oxygen fluorine neon
    sodium magnesium aluminium silicon phosphorus sulfur chlorine argon
    potassium calcium scandium titanium vanadium chromium manganese iron cobalt nickel copper zinc gallium germanium arsenic selenium bromine krypton
    rubidium strontium yttrium zirconium niobium molybdenum technetium ruthenium rhodium palladium silver cadmium indium tin antimony tellurium iodine xenon
    caesium barium lanthanum cerium praseodymium neodymium promethium samarium europium gadolinium terbium dysprosium holmium erbium thulium ytterbium lutetium hafnium tantalum tungsten rhenium osmium iridium platinum gold mercury (element) thallium lead bismuth polonium astatine radon
    francium radium actinium thorium protactinium uranium neptunium plutonium americium curium berkelium californium einsteinium fermium mendelevium nobelium lawrencium rutherfordium dubnium seaborgium bohrium hassium meitnerium darmstadtium roentgenium copernicium nihonium flerovium moscovium livermorium tennessine oganesson
    halogens  alkali metals
    iupac group number 18
    name by element helium group or
    neon group
    trivial name noble gases
    cas group number
    (us, pattern a-b-a)
    viiia
    old iupac number
    (europe, pattern a-b)
    0

    ↓ period
    1
    image: helium discharge tube
    helium (he)
    2
    2
    image: neon discharge tube
    neon (ne)
    10
    3
    image: argon discharge tube
    argon (ar)
    18
    4
    image: krypton discharge tube
    krypton (kr)
    36
    5
    image: xenon discharge tube
    xenon (xe)
    54
    6 radon (rn)
    86
    7 oganesson (og)
    118

    legend

    primordial element
    element by radioactive decay
    atomic number color: red=gas

    the noble gases (historically also the inert gases; sometimes referred to as aerogens[1]) make up a group of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low chemical reactivity. the six naturally occurring noble gases are helium (he), neon (ne), argon (ar), krypton (kr), xenon (xe), and the radioactive radon (rn). oganesson (og) is variously predicted to be a noble gas as well or to break the trend due to relativistic effects; its chemistry has not yet been investigated.

    for the first six periods of the periodic table, the noble gases are exactly the members of group 18. noble gases are typically highly unreactive except when under particular extreme conditions. the inertness of noble gases makes them very suitable in applications where reactions are not wanted. for example, argon is used in incandescent lamps to prevent the hot tungsten filament from oxidizing; also, helium is used in breathing gas by deep-sea divers to prevent oxygen, nitrogen and carbon dioxide (hypercapnia) toxicity.

    the properties of the noble gases can be well explained by modern theories of atomic structure: their outer shell of valence electrons is considered to be "full", giving them little tendency to participate in chemical reactions, and it has been possible to prepare only a few hundred noble gas compounds. the melting and boiling points for a given noble gas are close together, differing by less than 10 °c (18 °f); that is, they are liquids over only a small temperature range.

    neon, argon, krypton, and xenon are obtained from air in an air separation unit using the methods of liquefaction of gases and fractional distillation. helium is sourced from natural gas fields that have high concentrations of helium in the natural gas, using cryogenic gas separation techniques, and radon is usually isolated from the radioactive decay of dissolved radium, thorium, or uranium compounds. noble gases have several important applications in industries such as lighting, welding, and space exploration. a helium-oxygen breathing gas is often used by deep-sea divers at depths of seawater over 55 m (180 ft). after the risks caused by the flammability of hydrogen became apparent, it was replaced with helium in blimps and balloons.

  • history
  • physical and atomic properties
  • chemical properties
  • occurrence and production
  • applications
  • discharge color
  • see also
  • notes
  • references

Noble gases
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
halogens  alkali metals
IUPAC group number 18
Name by element helium group or
neon group
Trivial name noble gases
CAS group number
(US, pattern A-B-A)
VIIIA
old IUPAC number
(Europe, pattern A-B)
0

↓ Period
1
Image: Helium discharge tube
Helium (He)
2
2
Image: Neon discharge tube
Neon (Ne)
10
3
Image: Argon discharge tube
Argon (Ar)
18
4
Image: Krypton discharge tube
Krypton (Kr)
36
5
Image: Xenon discharge tube
Xenon (Xe)
54
6 Radon (Rn)
86
7 Oganesson (Og)
118

Legend

primordial element
element by radioactive decay
Atomic number color: red=gas

The noble gases (historically also the inert gases; sometimes referred to as aerogens[1]) make up a group of chemical elements with similar properties; under standard conditions, they are all odorless, colorless, monatomic gases with very low chemical reactivity. The six naturally occurring noble gases are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn). Oganesson (Og) is variously predicted to be a noble gas as well or to break the trend due to relativistic effects; its chemistry has not yet been investigated.

For the first six periods of the periodic table, the noble gases are exactly the members of group 18. Noble gases are typically highly unreactive except when under particular extreme conditions. The inertness of noble gases makes them very suitable in applications where reactions are not wanted. For example, argon is used in incandescent lamps to prevent the hot tungsten filament from oxidizing; also, helium is used in breathing gas by deep-sea divers to prevent oxygen, nitrogen and carbon dioxide (hypercapnia) toxicity.

The properties of the noble gases can be well explained by modern theories of atomic structure: their outer shell of valence electrons is considered to be "full", giving them little tendency to participate in chemical reactions, and it has been possible to prepare only a few hundred noble gas compounds. The melting and boiling points for a given noble gas are close together, differing by less than 10 °C (18 °F); that is, they are liquids over only a small temperature range.

Neon, argon, krypton, and xenon are obtained from air in an air separation unit using the methods of liquefaction of gases and fractional distillation. Helium is sourced from natural gas fields that have high concentrations of helium in the natural gas, using cryogenic gas separation techniques, and radon is usually isolated from the radioactive decay of dissolved radium, thorium, or uranium compounds. Noble gases have several important applications in industries such as lighting, welding, and space exploration. A helium-oxygen breathing gas is often used by deep-sea divers at depths of seawater over 55 m (180 ft). After the risks caused by the flammability of hydrogen became apparent, it was replaced with helium in blimps and balloons.