Group 7

What form group 7 molecules exist in?
Diatomic molecules
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Why do group 7 molecules have high boiling points?
Many electrons create strong van de waals forces meaning more energy is required to break them
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Why does electronegativity decrease going down the group?
Atomic radius and shielding
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Are group 7 molecules oxidising or reducing agents?
Oxidising agents
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What do group 7 molecules dissolve in?
Water and non-polar solvents (cyclohexane)
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What colour is formed when chlorine is dissolved in water and cyclohexane?
Pale green
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What colour is formed when bromine is dissolved in water and cyclohexane?
Orange
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What colour is formed when iodine is dissolved in water and cyclohexane?
Brown in water, violet in cyclohexane
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What is a halide?
A halogen which has gained electrons to form negatively charged ions
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Why is reactivity increased when going down halides?
Larger halides can lose electrons more easily due to less attraction to nucleus, therefore they have increased reducing ability
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What do sodium halides react with?
Concentrated sulfuric acid
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What happens when sodium chloride reacts with concentrated sulfuric acid?
Acidic gas given off, hydrogen halide given off
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What is the contents of the test tube?
White solid
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What products are formed from this reaction?
Sodium hydrogen sulphate, hydrogen chloride gas
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What happens when sodium bromide reacts with concentrated sulfuric acid?
Bromide ions reduce H2SO4 to create a 2nd exothermic reaction, white fumes, chocking acidic gas, hydrogen halide gas, acidic gas
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What is the contents of the test tube?
White solid, orange liquid
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What products are formed from this reaction?
Sodium hydrogen sulphate, hydrogen bromide gas, bromine, sulfur dioxide
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What happens when sodium bromide reacts with concentrated sulfuric acid?
Iodide ions further reduce, acidic gas, purple vapour, egg smell, hydrogen halide gas
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What is the contents of the test tube?
Black solid, yellow solid
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What products are formed from this reaction?
Sodium hydrogen sulphate, hydrogen iodide, iodine, sulfur, hydrogen sulfide
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How do you test for halide ions?
Add nitric acid to remove carbonates, add silver nitrate to form coloured precipitate, add dilute ammonia, add concentrated ammonia if not dissolved
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How do we know it's chloride?
Forms white precipitate, dissolves in dilute ammonia
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How do we know it's bromide?
Cream precipitate, dissolves in concentrated ammonia
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How do we know it's iodide?
Yellow precipitate, doesn't dissolve
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A reaction where an element is oxidised and reduced is called a
Disproportionation reaction
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What can chlorine make in disproportionation reactions?
Water treatment and bleach
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Other cards in this set

Card 2

Front

Why do group 7 molecules have high boiling points?

Back

Many electrons create strong van de waals forces meaning more energy is required to break them

Card 3

Front

Why does electronegativity decrease going down the group?

Back

Preview of the front of card 3

Card 4

Front

Are group 7 molecules oxidising or reducing agents?

Back

Preview of the front of card 4

Card 5

Front

What do group 7 molecules dissolve in?

Back

Preview of the front of card 5
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