* KS4 Science GCSE Chemistry Revision Notes  GROUP 0 NOBLE GASES helium, neon, argon, krypton, xenon

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Noble Gases Doc Brown's Chemistry  The GROUP 0 The Noble Gases 

Revision KS4 Science IGCSE/O level/GCSE Chemistry Information Study Notes for revising for AQA GCSE Science, Edexcel 360Science/IGCSE Chemistry & OCR 21stC Science, OCR Gateway Science  (revise courses equal to US grades 9-10)

Keywords * argon uses * compounds * data on elements * electron arrangement * helium uses * introduction * krypton uses * neon uses * radon dangers * xenon uses * uses of noble gases * extra information

GCSE m/c QUIZ on Noble Gases (xhtml version)

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GCE AS/A2/IB Advanced A Level Chemistry Notes on Noble Gases

Note: Using 0 to denote the Group number of Noble Gases is very historic now since compounds of xenon known exhibiting a valency of 8. Because of the horizontal series of elements e.g. like the Sc to Zn block (10 elements), Groups 3 to 7 can also be numbered as Groups 13 to 17, and Group 0 numbered Group 18, to fit in with the actual number of vertical columns of elements. This can make things confusing, but there it is, classification is still in progress!

Periodic Table

 

Introduction to the Group 0/8 Noble Gases (see data table below)

  • The "Noble Gases" are the last group in the Periodic Table i.e. they form the last elements at the end of a period.

  • They are all non-metallic elements and all are colourless gases at room temperature and pressure with very low melting points and boiling points.

  • They form 1% of air, and most of this is argon. All the noble gases, except radon, are separated by the fractional distillation of liquified air. Helium can also be obtained from natural gas wells where it has accumulated from radioactive decay (alpha particles become atoms of helium gas when they gain two electrons).

  • They are very unreactive elements because the highest occupied electron level is complete, meaning they have a full shell of outer electrons! (see diagrams below). They have no 'wish' electronically to share electrons to form a covalent bond or to lose or gain electrons to form an ionic bond. In other words, they are electronically very stable.

  • They exist as single atoms, that is they are monatomic He Ne Ar etc. (NOT diatomic molecules as with many other gases - reasons given above). This is because of their electronic stability - see point above and diagrams below.

  • Their very inertness is an important feature of their practical uses. 

  • Down the Group with increasing atomic number ...

    • the melting point and boiling point steadily increase (see data)

    • the density steadily increases (see data)

    • more likely to react and form a compound with very reactive elements like fluorine eg

      • Stable compounds of xenon are now known and synthesised BUT not before 1961!

    

The first 3 Noble Gases, showing their electron arrangements with full very stable outer shells. Noble Gases Noble Gases Noble Gases

  

Selected data on the Group 0/8 Noble Gases (more AS-A2 data)

Chemical symbol and name

 Atomic number Electron arrangement Melting point Boiling point Atomic radius pm (10-12m)
He helium 2 2 -272oC , 1K -269oC , 4K 49
Ne neon 10 2.8 -249oC , 24K -246oC , 27K 51
Ar argon 18 2.8.8 -189oC , 84K -186oC , 87K 94
Kr krypton 36 2.8.18.8 -157oC , 116K -152oC , 121K 109
Xe xenon 54 2.8.18.18.8 -112oC , 161K -108oC , 165K 130
Rn radon 86 2.8.18.32.18.8 -71oC , 202K -62oC , 211K 136

  

 Uses of the Group 0/8 Noble Gases
He helium Noble Gases The gas is much less dense than air (lighter) and is used in balloons and 'airships'. Because of its inertness it doesn't burn in air UNLIKE hydrogen which used to be used in large balloons with  'flammable' consequences e.g. like the R101 airship disaster! Helium is also used in gas mixtures for deep-sea divers.
Ne neon Noble Gasesjust like this website! Neon gives out light when high voltage electricity is passed through it, so its used in glowing 'neon' advertising signs and fluorescent lights. 
Ar argon Noble GasesNoble Gases Argon, like all the Noble Gases is chemically inert. It used in filament bulbs because the metal filament will not burn in Argon and it reduces evaporation of the metal filament. It is also used to produce an inert atmosphere in high temperature metallurgical processes, eg in welding where it reduces brittle oxide formation reducing the weld quality. Its bubbles are used to stir mixtures in steel production. Argon is the cheapest to produce.
Kr krypton   Not used by superman! BUT is used in fluorescent bulbs, flash bulbs and laser beams.
Xe xenon   Good for winning scrabble games! AND also used in fluorescent bulbs, flash bulbs and lasers.
Rn radon Noble Gases This has almost no uses, but does have dangers! Radio-isotopes of radon are produced by radioactive decay of heavy metals (e.g. uranium) in the ground. Can build up in cellars. Like all radio-isotopes it can cause cell damage (DNA) and ultimately cancer (see link below). However it is used in some forms of cancer treatment

  

Extra 'bits and bobs' on THE NOBLE GASES
% in Air by volume 0.0005% He, 0.0018% Ne, 0.93% Ar, 0.0001% Kr, 0.00001% Xe, ?% Rn - impossible to be zero, but an extremely minute trace hopefully! (varies with local geology)
Radon dangers Rocks, e.g. granite, can contain uranium metal compounds which are radioactive. When they 'decay' radioactively, radioactive and harmful radon gas can be formed.
Compounds of Noble Gases - yes they do exist! From the early 1960's compounds have been made, but only xenon compounds are stable and usually combined with oxygen and fluorine, which, not surprisingly, are the more reactive non-metals e.g.

Xe + 2F2 => XeF4 (using Ni catalyst 60oC, easy if you know how! and another catalytic bonus from a transition metal!)
   

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