31 . Reactivity with halogens : EX2 EX4 and EX6
The stability of halides decreases in the order F - > Cl - > Br - > I - . This is because E-X bond length increases with increase in size .
Among hexa halides , fluorides are the most stable because of steric reasons .
Dihalides are sp 3 hybridised , are tetrahedral in shape .
Hexafluorides are only stable halides which are gaseous and have sp 3 d 2 hybridisation and octahedral structure .
H2O is a liquid while H2S is a gas . This is because strong hydrogen bonding is present in water . This is due to small size and high electronegativity of O .
32 . Oxygen : Preparation :
Heat 2KClO 3 → 2KCl + 3O 2 MnO2 finely divided metals
2H2 O2 ( aq ) → 2H2 O ( l ) + O2 ( g )
heat 2Ag2O ( s ) → 4Ag ( s ) + O2 ( g )
2HgO ( s ) → 2Hg ( l ) + O2 ( g )
2Pb3O4 ( s ) → 6PbO ( s ) + O2 ( g ) ( Red lead )
2PbO2 ( s ) → 2PbO ( s ) + O2 ( g )