Group 7 Flashcards
colour of F2
pale yellow gas
Cl2 color
greengas
Br2 color
orange brown liquid
I2 color
grey solid with a purple vapor
what is the trend in volatilityas the elementsgo down the group
volatilitydecreasesas the boiling points increase
(volatilityis the ease at which a substancecan evaporate)
are london forces in halogens strong
not
how does an instantaneousinduced dipole form
electrons may randomly happen to be at one end of the molecule than the other
this gives one half of the molecule a much larger negative dipole
this will result in nearby molecules having an induced dipole
explain why the melting and boiling points of the halogen (cl2 Br2 etc) increase down the group
it is more difficult to seperate the two molecules
electron number increases so there is a greater instantaneousdipole formed
thus the London force is stronger
why does electronegativity decreasedown the group
atomic radii of elements increase due to an icreased number of complete inner shells
outer shells are further from the nucleus
incoming electron has weaker attraction to the nucleus
therfore the halogens ability to accept an electron is reduced-price
why does reactivity decrease down the group
atoms become larger and have more shielding
harder to accept an incoming electron due to a weaker attraction
so reactivity decreases
how to demonstrate the decrease in reactivity down the group of the halogen
reactions with hydrogen
reactions become less vigorous down group
what happens to bp down group
increases
what happens to colordown group
appearsdarker
how can a halogen displace another halogen from a halide solution
the more reactive halogen can displaced
example displacementreaction using Cl2 and 2NaBr
Cl2 (aq) + 2NaBr (aq) → 2NaCl (aq) + Br2 (aq)
are halogen displacementreactions redox eg.
Cl2 (aq) + 2I- (aq) → 2Cl- (aq) + I2 (aq)
yes
chlorine solution and potassium bromide
then with organic layer
yellow - orange (as bromine is formed)
organic layer will appearyelloworange
Cl2 (aq) + 2KBr (aq) → 2KCl (aq) + Br2 (aq)
chlorine solution and potassium iodide and organic layer
brown solution with purple organic layer as iodine is formed
Cl2 (aq) + 2KI (aq) → 2KCl (aq) + I2 (aq)
bromine and potassiumiodideand organic layer
solutionturns brown
porple organic layer
both as iodine is formed
Br2 (aq) + 2I- (aq) → 2Br- (aq) + I2 (aq)
redox reaction
what is oxidised when a halogen reacts with a group 1,2 metal
always the metal
reaction between sodium and chlorine
2Na (s) + Cl2 (g) → 2NaCl (s)
Na is being oxidised, the oxidation number is changing from 0 to +1
what happens when halogens react with iron
iron is oxidised by bromine and chlorine only as iodine is not strong enoughoxidizingagent- infacttheiodinewillbeoxidizeinstead
2I- (aq) + 2Fe3+ (aq) → I2 (aq) + 2Fe2+ (aq)
whatisadisproportionation reaction
a reaction where the same species is both oxidised and reduced simultaneously
what is oxidied andwhatisreducedwhenchlorinereactswithanalkaline
chlorineisreducedandalsooxidized
(disproportionstion)
howcanchlorinebeusedtomakesafedrinkingwaterwithequation
HClO (aq) → H+ (aq) + ClO- (aq)
chloric acidisasterilizersokillsbacteria
what happenswhenhalogensreactionwithsulfuricacid
toxicgasesareproducedsothesereactions need to be carried out inafume cupboard
H2SO4(aq) + X-(aq) → HX(g) + HSO4-(aq)
what colorisHCl gas
whitefumes
whathappenstothethermalstabilityofhydrogenhalite’sdownthegroup
decreases
reaction between hydrogen bromide and sulphuric acid
sulphuric acid is reduced to sulphur
hydrogen bromide is oxidised to bromine which is a redbrown gas
reaction between hydrogen iodide and sulphuric acid
hydrogen iodide is easiest hydrogen halide to decompose
sulphuric acid oxidises the hydrogen iodide into iodide which is a purple vapour
sulphuric acid is reduced into sulphur
6HI (g) + H2SO4 (aq) → 3I2 (g) + S (s) + 4H2O (l)
water byproduct
what forms when a halide reacts with silver nitrate
silver halide and ammoia solution
equation for halide ion + hydrogen
hydrogen halide produced
Cl2 (g) + H2 (g) → 2HCl (g)
how to identify what halide is in a silver halide solution
add concentrated ammonia and a dilute
if precipitate only dissolves in the dilute it is bromide
if it doesnt dissolve in either it is iodide
if it only dissolves in ammonia it is chloride
equation for the reaction between a hydrogen halide and ammonia
ammonium halide formed
NH3 (g) + HCl (g) → NH4Cl (s)
hydrogen halide and water reaction
dissolves to form H3O and CL
