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Noble Gases
Fr Ra Ac Rf Db Sg Bh Hs Mt Ds Rg ? ? ? ? ? ? ? Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br
Na Mg Al Si P S Cl
Li Be B C N O F
H
Rn Xe Kr Ar Ne He
Noble Gases
Noble Gases
Why are noble gases so unreactive?
Why NOBLE GASES are inert in nature?
Chemical Inertness of these gases is due to following reasons:
I. The atoms have stable completely field electronic shells II. They have high ionization energies
III. The noble have almost zero electron affinities.
Therefore, they do not have any tendency to gain, lose or share
electrons with other atoms.
helium 2
neon 2,8
argon 2,8,8
Electron structure and reactivity
They do not normally form bonds with other elements.
All noble gases have full outer electron shells and do not need to gain, lose or share electrons.
They are very stable and the most
unreactive (or inert) of all the elements.
They are monatomic, which means they exist as individual atoms. Most other gases are
diatomic.
This means that:
8
Group 8 becomes group 0
Why is group 0 not called group 8, even though it comes after group 7?
In the rest of the periodic table, the number of the group is the same as the number of outer shell electrons in the elements of that group.
However, this is not true for the noble gases. Helium only has 2 electrons in its outer shell, while the others all have 8. The group’s number was changed to 0 because of this.
Rn Xe Kr Ar Ne He 0
It used to be called group 8, and still is in some cases.
Compounds of noble gases
• XeF
2• XeF
4• XeF
6• XeO
3• XeO
2F
2• XeOF
4• XeO
4• XeO
3F
2Uses of noble gases
Although noble gases are unreactive, they are still very useful elements.
Many uses of noble gases depend on their ability to prevent other, undesirable, reactions taking place.
Uses of helium
The gas for inflating balloons and airships, because it is less dense than air and inflammable.
A protective gas for growing silicon crystals in silicon chip manufacture, because it is unreactive.
A component of breathing gas (with oxygen) for deep-sea divers, because it is unreactive, insoluble and prevents divers getting ‘the bends’.
Helium is used as:
A super-coolant for high-performance
magnets, e.g. in body scanners, because it has a very low boiling point (-269°C).
Uses of neon
Neon is used:
In ‘neon’ advertising signs, because it glows red when an electric current is passed
through it.
In TV tubes.
In certain types of lasers.
As a cryogenic refrigerant (when liquid).
Uses of argon
Argon is used:
In normal light bulbs, because it is unreactive and prevents the tungsten filament from burning.
In energy-efficient fluorescent light bulbs.
As a ‘gas blanket’ for arc welding, because it is unreactive and prevents the hot welding metal from oxidizing.
Uses of other noble gases
Krypton is used:
In lasers for eye surgery, to stop bleeding on the retina.
In lighthouses and other types of lamps.
In various types of electron tubes, lamps and lasers.
Xenon is used:
Radon is used:
To treat cancer by radiotherapy, because it is radioactive.
However, because radon is radioactive, it is also an environmental hazard.
