Group 17 Flashcards
Chlorine
Green/yellow gas
Bromine
Dark red liquid
Iodine
Dark grey solid
Volatility trend
Decreases down the group
There are Van der Waals forces between the two molecules, these forces increase down the group as the number of electrons increases
The greater number of electrons, the greater opportunity for instantaneous dipoles to occur and so for induced dipoles to be produced
Halogens act as oxidising agents, what is the trend of oxidising ability
The oxidising power of halogens lessens going down the group as their reactivity lessens
Halogens plus hydrogen gas
Hydrogen halides
Fluorine plus hydrogen
Reacts explosively even in cool, dark conditions
Chlorine plus hydrogen
Reacts explosively in sunlight
Bromine plus hydrogen
Reacts slowly on heating
Iodine plus hydrogen
Forms an equilibrium mixture on heating
The thermal stability of the hydrogen halides decreases down the group as the bond strength decreases, this can be shown by inserting a red hot wire into them
HCl is unchanged
HBr may show a slight brown colouration due to some Br being formed
HI shows a cloud of purple vapour showing the decomposition of the gas
Why does the thermal stability of hydrogen halides decreases down the group
The small molecules of hydrogen halides have permanent dipole attractions between them
Down the group the bond length increases as the radius of the halogen atom increases this leads the bond strength to decrease because the bond pair of electrons is further from the nucleus as you go down the group
Sulfuric acid is used as
An oxidising agent
It gets easier to oxidise the hydrogen halides going down the group
Chlorine undergoes disproportionation when it reacts with an alkali this means
Some chlorine atoms are reduced and some are oxidised in the same reaction
Chlorine and cold sodium hydroxide produces
NaCl+NaClO+H2O
