Shaktipriya Patra KV Cossipore

1. Presented by -
Shaktipriya Patra
K V Cossipore
Class : XII B
Roll No. : 44

2. GROUP 18 ELEMENTS
Name of the
Element
Symbol Atomic no. Electronic
configuration
Helium He 2 1s2
Neon Ne 8 [He]2s22p6
Argon Ar 18 [Ne]3s23p6
Krypton Kr 36 [Ar]3d104s24p6
Xenon Xe 54 [Kr]4d105s25p6
Radon Rn 86 [Xe]4f145d106s26p6
Oganesson Og 118 [Rn]5f146d107s27p6
General electronic configuration:- ns2np6
Exception He (1s2 )

3. Some physical properties
• Noble gases are monoatomic.
• They are colorless, odourless and tasteless.
• Sparingly soluble in water.

4. Physical properties…
Element Atomic
mass(g/mol)
Atomic
radius (pm)
Density (g/cm3 )
(at STP)
He 4.00 120 1.8x10-4
Ne 20.18 160 9.0x10-4
Ar 39.95 190 1.8x10-3
Kr 83.80 200 3.7x10-3
Xe 131.30 220 5.9x10-3
Rn 222.00 - 9.7x10-3
Increasingatomicradii

5. Physical properties…
Elements Ionization
enthalpy(kJ/mol)
Electron gain
enthalpy(kJ/mol)
He 2372 48
Ne 2080 116
Ar 1520 96
Kr 1351 96
Xe 1170 77
Rn 1037 68
 Ionization enthalpy of noble gases are very high due to stable electronic
configuration and it decreases down the group with increase in atomic size.
 The electron gain enthalpy for noble gases have large positive value due to
stable electronic configuration.

6. Physical properties…
Elements Melting point(K) Boiling point(K)
He - 4.2
Ne 24.6 27.1
Ar 83.8 87.2
Kr 115.9 119.7
Xe 161.3 165.0
Rn 202 211
Noble gases have very low melting and boiling points.
Reason:-presence of only weak dispersion forces.
Helium has the lowest boiling point(4.2K) of any known
substance.

7. Chemical properties
Noble gases are least reactive or inert.
Reason :-
(i) The noble gases except helium (1s2) have completely
filled ns2np6 electronic configuration in their valence
shell.
(ii) They have high ionization enthalpy and more
positive electron gain enthalpy.

8. • till date.
Neil Bartlett in 1962 was
successful in preparing
first compound
containing a noble gas, a
red color compound
Xe+PtF6– by mixing
PtF6 and xenon.
No true
compounds of
Ar, Ne or He
are known

9. Xenon-fluorine compounds
XeF6 can also be prepared by the interaction of
XeF4 and O2F2 at 143K.

10. XeF2
XeF4
XeF6

11.  Xenon fluorides react with fluoride ion acceptors to
form cationic species:-
 Xenon fluorides react with fluoride ion donors to
form fluoroanions:-

12. Xenon-oxygen compounds
 Hydrolysis of XeF4 and XeF6 with water gives
Xe03.
 Partial hydrolysis of XeF6 gives oxyfluorides,
XeOF4and XeO2F2.

13. XeO3 is a colorless
explosive solid and has a
pyramidal molecular
structure
XeOF4 is a colorless
volatile liquid and has a
square pyramidal
molecular structure

14. Other compounds
containing noble gases
KrF2 RnF2

15. Uses of noble gases
Helium
• non-inflammable and light gas
• used in filling balloons for meteorological
observations
• used in gas-cooled nuclear reactors
• In modern NMR spectrometers and Magnetic
Resonance Imaging (MRI)
• Liquid helium (b.p. 4.2 K) is used as cryogenic agent
• used as a diluent for oxygen in modern diving
apparatus

16. Neon
• The largest use of neon is in making the ubiquitous
‘neon signs’ for advertising. In a vacuum discharge
tube neon glows a reddish orange colour.
• Neon bulbs are used in botanical gardens and in
green houses.
• Neon is also used to make high-voltage indicators
and switching gear, lightning arresters, diving
equipment and lasers.
• Liquid neon is an important cryogenic refrigerant.

17. Argon
• Used to provide an inert atmosphere in high
temperature metallurgical processes
• for filling electric bulbs.
Xenon and Krypton
• used in light
• bulbs designed for special purposes