Halogens Flashcards
What letter often represents a halogen
X
What outer shell configurations do all group 7 have
P5
What state do all natural group 7 elements exists as
Diatomic molecules
Single cov bond
Covalent radius trend down group 7
Increases
More electrons
More electron shells
Take up more space
Ionisation energy trend going down group 7
Decreases
Outer electron further from nucleus
Less ESA
Easier to remove
Electron affinity trend down group 7
Decreases
Expect F (lower than Cl)
Ionic radius down group trend group 7
Increases
Electronegativity trend down group 7
Decreases
I same as C (C-I basically non-polar)
F2 state, appearance room temp, aqueous solutions, dissolved hydrocarbon solvent
Pale yellow gas
Virtuallly colourless
Virtually colourless
Cl2 state, appearance room temp, aqueous solutions, dissolved hydrocarbon solvent
Green gas, virtually colourless, pale yellow
Br2 state, appearance room temp, aqueous solutions, dissolved hydrocarbon solvent
Red/brown liquid, yellow, orange
I2 state, appearance room temp, aqueous solutions, dissolved hydrocarbon solvent
Grey metal looking solid, orange/brown, purple
Group 7 solubility
Non-polar molecules
High solubility in no-polar solvents
Limited solubility in water
Bubble Cl2 gas through water
Makes chlorine water
Mixture of dissolved Cl2 and disproportionation between Cl2 and H2O
NaHOCl (aq)
Bleach
Why do halogens dissolve in hydrocarbon solvent and what colour do they take on
Both non-polar molecules
Cl- green/yellow
Br- brown/orange
I- purple
How does iodine dissolve in water
In a KI solution
I2(s) + I-(aq) —> I3-(aq)
What do all halogens act as and then become
Oxidising agents
Become halides
Oxidisation power trend group 7
Decreases down group
What do all halide ions act as and then become
Reducing agents
Halogens
Reducing power trend group 7
Increases down group
Describe a test for halide ions
Nitric acid (remove carbonate ions, misleading white ppte)
Silver nitrate form..
White ppte - chloride
Cream ppte - bromide
Yellow ppte - iodide
Another test for halide ions
Add dilute ammonia solution
Cl- dissolves
Add conc ammonia solution
Br- dissolves
I- never dissolves
Litmus hydrogen halide test
Turn damp blue litmus red
How do halogens react with ammonia gas
Make ammonium halide compound
Ionic solid
White smoke
Can hydrogen halides dissolve in water
Yes
Disassociate
Acidic solutions
Every HCl disassociated: strong acid
Hydronium/hydroxonium ion
H3O+
Shown as H+
Potassium halide reactions with sulfuric acid
Chlorines
KCl(s) + H2SO4(aq) —> KHSO4(s) + HCl(g)
Bromines
KBr(s) + H2SO4(aq) —> KHSO4(s) + HBr(g)
HBr reduces S from +6 to +4
2HBr(g) = H2SO4(aq) —> Br2(g) + SO2(g) + 2H2O(l)
Iodines
No HI survives, reduces S from +6 to 0/-2
8HI(g) + H2SO4(aq) —> H2S(g) + 4I2(g) + 4H2O(l)
Carbonate ion test
Add acid
Fizzing
CO2 produced
Bubble through limewater colourless —> cloudy
Solid or solution
Sulfate ion test
HCl, react with carbonate ions that might give a false positive
Add barium chloride solution
White ppte
Ammonium ions test
Add sodium hydroxide
Gently heat
Damp red litmus over gas
Turns blue
Ammonia is a base
Makes white smoke with HCl vapour
Halates and oxidation numbers
+1 ClO- (I)
+3 ClO2- (III)
+5 ClO3- (V)
+7 ClO4- (VII)
Halate oxidising power trend
Produce halogen or halide
Increase ox number, increase oxidising power
Halogens with cold aqueous hydroxide
Then heated
Cl2 + 2OH- —> ClO- + Cl- + H2O
3ClO- —> ClO3- + 2Cl-
3Cl2 + 6OH- —> ClO3- + 5Cl- + 3H2O
Disproportionation easier down group, lower temp needed
