pooja sharma ppt

SOFTVISION COLLEGE : 

PRESENTED BY- SAPNA SHARMA B.Sc 2 nd SEM SOFTVISION COLLEGE

NOBLE GASES: 

NOBLE GASES INTRODUCTION He Ne Kr Xe Ar Ra

POSITION IN PERIODIC TABLE: 

POSITION IN PERIODIC TABLE Electronegative elements Noble gases Electopositive elements F=9 He=2 Li=3 Cl =17 Ne=10 Na=11 Br=35 Ar =18 K=19 I=53 Kr=36 Rb =37 At=85 Xe =54 Cs=55 Ra=86 Fr=87

General Properties : 

General Properties PHYSICAL PROPERTIES- (1) All of them are colourless gases. (2) The ratio of their specific heats at constant pressure &constant value Cp/ C v is 1.66, which shows that they are monoatomic . (3) They liquefy and solidify at exceedingly low temperature. (4) The inert gases have a fairly high electrical conductivity. When sparked at l ow pressure in a discharge tube they emit characteristics coloured lights. (5) The inert gases have a relatively high solubility in water. (6) All the rare gases except. they are more or less readily absorbed by active wood charcoal at low temperatures. ELECTRONIC CONFIGURATION AND INERTNESS . Helium has its complete duplet and all other gases have an octet of elements in their outer shell. This electronic configuration renders them inert.

3) HIGH IONISATION ENERGY- : 

3) HIGH IONISATION ENERGY- The atoms of these gases have an electron affinity near to zero and have higher ionisation energeis than any other element. Consequently, they neither gain nor lose electrons under normal conditions and hence they do not from any bonds.Being bondless they exist as single atoms. The only forces that keep the atoms together are weak van der waal’s forces ,so their boiling points are also very low.

REAL CEMICAL COMPOUNDS OF NOBLE GASES The first chemical compound of noble gases was reported by N.Bartlett in 1962. The preparation of this compound, XeptF6was based on the accidental discovery of another compound formed by the reaction between oxygen gas and platinum hexafluoride. O2(g) + PtF6(g) O2[ptF6](s) : 

REAL CEMICAL COMPOUNDS OF NOBLE GASES The first chemical compound of noble gases was reported by N.Bartlett in 1962. The preparation of this compound, XeptF6was based on the accidental discovery of another compound formed by the reaction between oxygen gas and platinum hexafluoride. O2(g) + PtF6(g) O2[ptF6](s)

COMPOUNDS OF XENON: 

COMPOUNDS OF XENON a) Xenon Difluoride (XeF2) Structure of xeF2- 1) sp3d hybridization. 2) Trigonal bipyramidal structure. 3)The F- Xe -F bond angle is 180&Xe-F bond length is 2.0A. The shape of the molecule is linear instead of T.B.P.

b) Xenon tetrafluoride(xeF4): 

b) Xenon tetrafluoride (xeF4) Structure of XeF4- Hybridization of xef4 Sp3d2. Structure octahedral.on account of the fact that lp-lp repulsion> lp-lp repulsion> bp-bp repulsion,there is some disortion in the shape of the molecules . Thus ,XeF4 has disorted octahedral geometry with two lone pairs of electrons. In other words, it has a squar planar geometry.

Xenon haxafluoride(xeF6): 

Xenon haxafluoride (xeF6) Structure of XeF6 molecules- Sp3d3 hybridization. The exepected geometry is pentagonal bipyramidal , but due to the fact that.lp-lp repulsion > bp-bp repulsion there is some disortion in the shape of the molecules. Thus ,xef6 has disorted pentagonal bipyramidal structure with one lone pair of electones .

Monoatomic nature of noble gases-: 

a)High ionization b) Refrective index c) Dielectri constant Monoatomic nature of noble gases-

XeF8-molecules-: 

Xenon octafluoride XeF8-molecules-