12 - group 17 Flashcards

1
Q

what are halogens

A

what group 17 elements are called, 7 electrons in outer shell

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2
Q

flourine electronic configuration

A

1s²
2s², 2p5

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3
Q

cholrine electronic configuration

A

1s²
2s², 2p6
3s², 3p5

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4
Q

bromine electronic configuration

A

1s²
2s², 2p6
3s², 3p6, 3d10
4s², 4p5

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5
Q

iodine electronic configuration

A

1s²
2s², 2p6
3s², 3p6, 3d10
4s², 4p6, 4d10
5s², 5p5

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6
Q

group 17 elements properties?

A

. all non metals
. diatomic molecules at room temperature
. single covalent bond betwee. two atoms in each molecule

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7
Q

F, Cl, Br, I (–>)

A

. atomic radius increases
. melting and boiling point increase
. volatility decreases
. reactivity decreases
. electronegativity decreases
. strength as oxidising agent decreases
. bond energy decreases
. thermal stability decreases
. increasing effectiveness as reducing agents
. ease to oxidise hydrogen halides increases

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8
Q

what is volatility

A

the ease with which a substance evaporates

g17 have low values (simple molecular structures, weak id-id)

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9
Q

F colour

A

pale yellow gas

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10
Q

Cl colour

A

green/yellow gas

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11
Q

bromine colour

A

orange/brown liquid

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12
Q

iodine colour

A

. grey/black liquid
. purple gas

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13
Q

reactions of halogens

A

. halogens + metals (h is oxidising agent) IONIC BOND
. halogens + non metals (h is oxidising agent) COVALENT BOND

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14
Q

vigorous

A

a reaction that has a rapid rate of reaction

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15
Q

more reactive halogens displace less reactive ones in a reaction

A
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16
Q

immiscible

A

two liquids that do not dissolve in each other and so form two seperate layers, such as oil and water

17
Q

which colourless liquid do the halogens dissolve well in

A

cyclohexane

18
Q

flourine + hydrogen

A

H2 + F2 = 2HF
. explosive even in cool, dark conditions

19
Q

cholrine + hydrogen

A

H2 + Cl2 = 2HCl
. explosive in sunlight

20
Q

bromine + hydrogen

A

H2 + Br2 = 2HBr
. reacts slowly on heating

21
Q

hydrogen + iodine

A

H2 + I2 =REVERSIBLE= 2HI
. forms equilibrium mixture on mixing

22
Q

thermal stability

A

the resistance of a compound to breakdown by heating

23
Q

test for halide ions:

A

1) add dilute nitric acid and aqueous silver nitrate
. AgCl, white
. AgBr, cream
. AgI, pale yellow

AgNO3 + X¯ - - - - > AgX + NO3¯

2) add dilute and concentrated ammonia solution
. AgCl - dissolves, dissolves
. AgBr - insoluble, dissolves
. AgI - insoluble, insoluble

24
Q

halide ions and concentrated sulfuric acid

A

ALL PRODUCE TOXIC GASES

CHLORINE
NaCl + H2SO4 - - - > NaHSO4 + HCl
white fumes

BROMINE
NaBr + H2SO4 - - - > NaHSO4 + HBr
2HBr + H2SO4 - - - > Br2 + SO2 + 2H2O
red brown gas

IODINE
NaI + H2SO4 - - - > NaHSO4 + HI
2HI + H2SO4 - - - > I2 + SO2 + 2H2O
6HI + H2SO4 - - - > 3I2 + S + 2H2O
8HI + H2SO4 - - - > 4I2 + H2S + 4H2O
. sulfur yellow solid
. hydrogen sulfate with bad egg smell
. iodine as purple vapour

25
Q

disproportionation reaction

A

self-reduction / oxidation reaction
undergone by cholrine

26
Q

chlorine in cold alkali - 15°C (disproportionation reaction)

A

Cl2 + 2NaOH - - - > NaCl + NaClO SODIUM CHLORATE + H2O

. reduction
0.5Cl2 + e¯ = Cl¯

. oxidation
0.5Cl2 + 2OH¯= ClO¯ + H2O + e¯

27
Q

chlorine in hot alkali - 70°C (disproportionation reaction)

A

3Cl2 + 6NaOH - - - > 5NaCl + NaClO3 SODIUM CHLORATE + 3H2O

. reduction
Cl2 to NaCl
0 to - 1

. oxidation
Cl2 to NaClO
0 to +5

28
Q

adding chlorine in water makes water safer to drink

A
29
Q

chlorine disproportionation reaction in water

A

Cl2 + H2O - - - > HCl + HClO
0,, - 1, +1

30
Q

HClO

A

chloric I acid
sterilies water by killing bacteria
some dissolves in water to produce ClO- (this acts as a sterilising agent)