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Chemistry > Chapter 8 - Group 2 and Halogens > Flashcards

Chapter 8 - Group 2 and Halogens Flashcards

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1
Q

physical properties of group 2 metals?

A
  • high melting points
  • light
  • low densities
  • form colourless white compounds (precipitates)
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2
Q

explain the reactivity trend down group 2

A

increases

  • an electron at a higher energy level
  • thus larger atomic radius
  • less nuclear attraction
  • easier to lose electrons
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3
Q

redox reactions of group 2?

A

are reducing agents

  • are oxidised themselves
  • lose electrons
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4
Q

redox reaction with oxygen of group 2?

A

react vigorously to from a form metal oxide

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5
Q

how does magnesium react with oxygen?

A

magnesium burns with a brilliant white light and forms a white precipitate

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6
Q

group 2 reaction with water? is it a redox reaction?

A

all except beryllium react

  • form hydroxides
  • hydrogen gas also formed
  • yes, redox
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7
Q

group 2 reaction with dilute acid? is it redox?

A
  • form a soluble salt
  • and hydrogen
  • yes, redox
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8
Q

explain the trend in ionisation energy down group 2?

A
  • decreases
  • larger atomic radius
  • more electron sheilding
  • less nuclear attraction
  • electrons easily lost
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9
Q

group 2 oxide reaction with water?

A
  • release hydroxide ions
  • form alkaline solutions
  • metal hydroxide
  • when saturated, will form a white precipitate
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10
Q

trend in the solubility of group 2 hydroxides down the group?

A

increases, as they release more OH- ions as you go down, making the solution more alkaline

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11
Q

state the uses of group 2 compounds as bases? elaborate later

A
  • agriculture
  • medicine
  • construction
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12
Q

describe how group 2 compound bases are used in agriculture?

A
  • calcium hydroxide used as ‘lime’ by farmers

- reduces the acidity of the soil

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13
Q

describe how group 2 compound bases are used in medicine? why is it safe to swallow?

A
  • indigestion = too much hydrochloric acid in stomach
  • magnesium hydroxide neutralises excess stomach acid
  • ‘milk of magnesia’
  • not concentrated
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14
Q

describe how group 2 compound bases are used in construction? DRAWBACK OF USAGE?

A

calcium carbonate present in limestone and marble

  • use din manufacture of glass and steel
  • DRAWBACK readily react with acid causing acid rain
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15
Q

general physical properties of group 17 halogens?

A
  • low melting and boiling point

- exist as diatomic molecules

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16
Q

why does the boiling point increase as you go down group 17?

A
  • more electrons
  • stronger London forces
  • more energy required to break the IMF
  • boiling point increases
17
Q

appearance of each halogen at RTP?

A
  • fluorine: pale yellow gas
  • chlorine: pale green gas
  • bromine: red-brown liquid
  • iodine: shiny grey-black solid
  • astatine: never been seen
18
Q

electron configuration of group 17 elements?

A

7 outer shells

  • 2 in s subshell
  • 5 in p subshell
  • in p block
19
Q

redox reactions of group 17?

A

are oxidising agents

- reduced themselves

20
Q

purpose of displacement reactions of halogens with halides?

A

show that reactivity decreases down the group

21
Q

method for halogen-halide displacement reaction?

A
  • solution of halogen added to an aqueous solution of another halide
  • reaction take place
  • solution colour changes
22
Q

what do we do to bromine and iodine in the displacement reaction and why?

A

because iodine and bromine appear simliar in colour in solution with water, they are added cyclohexane

23
Q

why does the step taken for bromine and iodine work?

A
  • cyclohexane is a non-polar organic solvent
  • halogens are non-polar
  • COLOURS much easier to tell apart
  • iodine: orange
  • bromine: deep violet
24
Q

results of halogen-halide displacement reaction?

A
  • chlorine reacts with both Br- and I-
  • bromine only with I-
  • iodine doesn’t react at all
25
Q

explain the trend of reactivity down group 17

A
  • atomic radius increases
  • more shielding
  • less nuclear attraction with the electron of another species
  • reactivity decreases
26
Q

which is the stongest oxidising agent?

A

fluorine

27
Q

what is a disproportionation reaction?

A
  • redox reaction in which the same element is both oxidised and reduced
28
Q

reaction of chlorine with water? equation and products?

A
  • disproportionation reaction occurs

- chlorine + water -> chloric (I) acid + hydrochloric acid

29
Q

uses of chlorine + water reaction, test afterwards?

A

chloric (I) acid AND chlorate (I) ions kill bacteria

- weak bleach, litmus paper red (acidic), then bleached

30
Q

the reaction of chlorine + cold dilute aqueous sodium hydroxide?

A
  • disproportionation reaction
  • by itself, chlorine not very soluble
  • with NaOH much more dissolves
  • chlorate (I) from sodium chlorate produced
31
Q

benefits and risks of chlorine usage?

A

+ purifies water
+ rids it from typhoid, cholera
- toxic gas
- respiratory irritant in low concentrations
- fatal in large concentrations
- can react with organic compounds like methane, suspected of causing cancer

32
Q

redox ability of halogens and halide ions? which one cannot reduce and which one CAN?

A

halogens- oxidising agents
halide ions- reducing agents
- can be shown by reading with sulfuric acid, halides oxidised to form halogens
- HOWEVER, chlorine atoms cannot, bromide ions and iodide ions can

33
Q

carbonate test?

A
  • add any dilute acid
  • bubbles of CO2 produced
  • tets with ilmewater
  • white precipitate of carbonate
34
Q

sulfate test?

A
  • add barium nitrate/chloride

- white precipitate of barium sulfate

35
Q

halide test?

A
  • add aqueous silver nitrate
  • different colour precipitate
  • chloride: white
  • bromide: cream
  • iodide: yellow
36
Q

what additional test after halide test? why?

A
  • add ammonia solution
  • chlorine dissolves in all concentrations
  • bromine dissolves in concentrated solutions
  • iodine in no concentration
37
Q

order of ion tests and why?

A
  • carbonate, sulfate, halide
  • all precipitates white
  • will give false positive results
38
Q

test for ammonium ion?

A
  • add aqeous sodium hydroxide
  • ammonia gas produced
  • mixture WARMED
  • gas released
39
Q

observation/further tests during ammonium ion test? PRECAUTION?

A
  • ammonia gas produced
  • BUT
  • won’t see gas bubbles because ammonia very soluble
  • smells burnt and fleshy
  • alkaline so turns litmus paper blue
  • HAZARDOUS, test with care

Chemistry (14 decks)

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