Group 7 The Halogens

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Cards (37)

What‘s the trend of boiling points down the group?
Increase
Why do the boiling points increase down the group?
Increased molecular size, more electrons and the van der Waals are stronger between the molecules and so require more energy to overcome
What’s trend of electronegativity down the group?
Decreases
Why does electronegativity decrease down the group?
There’s a greater nuclear charge, larger atomic radius and more shielding
What’s the most electronegative element?
Fluorine
What’s the most reactive halogen?
Fluorine
What’s the appearance of fluorine?
Pale yellow gas
What’s the appearance of chlorine?
Pale green gas
What’s the appearance of bromine?
Red-orange liquid
What’s the appearance of iodine?
Black solid with purple vapour
What halogen has the greatest oxidising power?
Fluorine
What’s the trend of reducing agents down the group?
Increasing reducing power
Why does the reducing power of halogens increase down the group?
Ions are larger, more shielding (due to extra electron shell)
Which halogen is the poorest reducing agent?
Fluorine
Which halogen is the best reducing agent?
iodine
What are the observations when chloride ions react with concentrated sulphuric acid?
steamy white fumes as hydrogen chloride gas is produced and effervescence
What are the observations when bromide ions react with concentrated sulfuric acid?
Steamy fumes as HBr is produced, effervescence, Br2 as brown fumes, SO2 as a colourless gas
What are the observations when iodide reacts with conc sulfuric acid?
steamy white fumes as HI is produced, effervescenc, I2 as purple fumes/ black solid, SO2 as colourless gas, S as a yellow solid and H2S smells of rotten eggs
What reaction takes place when halide ions react with concentrated sulfuric acid?
acid/base reaction
What is a disproportionation reaction?
A reaction in which the same species is simultaneously oxidized and reduced.
What is the reaction for bleach?
Mixing chlorine gas with cold, dilute sodium hydroxide solution at room temperature, sodium chlorate (I) solution is formed
What’s the equation for making bleach?
$2NaOH$ + $Cl_2$ -> $NaClO$ + $H_2O$ + $NaCl$
How can you test for the presence of halide ions?
Add acidified silver nitrate to the test solution
What is the reactant formed when chloride ions react with acidified silver nitrate?
White precipitate
What is the reactant formed when acidified silver nitrate reacts with bromide ions?
A cream precipitate
What is the reactant formed when acidified silver nitrate reacts with iodide ions?
A yellow precipitate
What happens to the chloride precipitate when dilute ammonia is added?
The precipitate will dissolve
What happen to the bromide precipitate when dilute ammonia is added?
No change
What happens to the iodide precipitate when dilute ammonia is added?
No change
What happens to the chloride precipitate when concentrated ammonia is added?
The precipitate will dissolve
What happens to the bromide precipitate when concentrated ammonia is added?
The precipitate will dissolve
What happens to the iodide precipitate when concentrated ammonia is added?
No change
What products and type of reaction occurs when chlorine reacts with COLD water?
A disproportionation reaction occurs, chlorate ions (ClO-) and chloride ions
What happens t chlorine and water under the presence of UV light?
Chlorine decomposes to produce oxygen and hydrochloric acid
Chlorine is reduced
How can you test for sulfates?
The addition of BaCl2, if sulfates present a white precipitate will be formed
What is the test for hydroxide ions?
Red litmus paper, will turn blue due to the alkaline nature of hydroxide ions
What’s the test for carbonate ions?
The addition of an acid like HCl, the carbonate ions will fizzle (effervescence) and carbon dioxide will be given off. The gas is collected and bubbled through limewater which will turn cloudy to confirm the gas as CO2