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Chemistry > Topic 4 - Group 2 and 7 > Flashcards

Topic 4 - Group 2 and 7 Flashcards

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1
Q

what are the group 2 elements?

A

beryllium, magnesium, calcium, strontium and barium

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2
Q

what is the trend of atomic radius down Group 2?

A

it increases, as one extra shell of electrons is added

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3
Q

what is the trend of melting points down Group 2?

A

melting points decrease - as atomic size increases the metallic bonding weakens

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4
Q

what is the trend of reactivity down Group 2?

A

it increases, because it is easier to remove the outer electron due to the increased distance

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5
Q

what metal burns with a lilac flame?

A

potassium

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6
Q

what metal burns with a red or blue flame?

A

rubidium

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7
Q

what metal burns with a brick red flame?

A

calcium

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8
Q

what metal burns with a green flame?

A

barium

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9
Q

what metal burns with a red flame?

A

strontium

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10
Q

what metal burns with a blue flame?

A

caesium

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11
Q

what Group 2 metal reacts in steam?

A

magnesium

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12
Q

what are the observations of Group 2 Metal + water?

A

effervescence, heating up, dissolving

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13
Q

what do Group 2 metal react with cold water to form?

A

hydroxides

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14
Q

what does magnesium react with steam to form?

A

magnesium oxide and hydrogen

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15
Q

what does magnesium react with warm water to form?

A

magnesium hydroxide and hydrogen

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16
Q

group 2 metal + oxygen -> ?

A

metal oxide

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17
Q

group 2 metal oxide + water -> ?

A

hydroxides

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18
Q

group 2 metal oxide + acid -> ?

A

salt and water

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19
Q

describe the solubility trend down Group 2 hydroxides

A

they become more soluble down the group

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20
Q

describe the solubility trend down Group 2 sulfates

A

they become less soluble down the group

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21
Q

what is thermal decomposition?

A

the use of heat to break down a reactant into more than one product

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22
Q

what do Group 2 carbonates decompose to?

A

group 2 oxides and CO2

23
Q

describe the thermal stability of Group 2 carbonates down the group

A

they become more thermally stable, because as the cations get bigger, they have less polarizing and distort the carbonate ion less

24
Q

describe the method of a flame test

A
  1. use a nichrome wire
  2. clean it by dipping it into concentrated hydrochloric acid then heating
  3. dip wire in solid then put into flame
25
Q

describe the flame tests as proof of existence of ions

A

in a flame test the heat causes the electron to gain energy and move to a higher energy level.
when it falls down due to the instability, it emits energy in the form of visible light (photons)

26
Q

what are the Group 7 elements?

A

fluorine, chlorine, bromine and iodine

27
Q

what is fluorine at room temperature?

A

pale yellow gas

28
Q

what is chlorine at room temperature?

A

light green gas

29
Q

what is bromine at room temperature?

A

red-brown liquid

30
Q

what is iodine at room temperature?

A

black solid, sublimes to purple gas

31
Q

what is the trend in melting/boiling points down Group 7?

A

increases down the group

  • as electrons are added, London forces get stronger
  • more energy required to break them
32
Q

what is the trend in electronegativity down Group 7?

A

decreases down the group

  • atomic radius increases due to the increasing number of shells
  • the nucleus is weaker and cannot attract the bonding pair
33
Q

what is the trend in reactivity down Group 7?

A

decreases

  • atoms get bigger
  • more shielding
  • harder to attract and accept electrons
34
Q

are halogens reducing or oxidising agents?

A

electron acceptor (forms -1 ions) o therefore oxidising agent

35
Q

what is the trend in oxidising strength down Group 7?

A

decreases down the group, it will displace the halogen below it from one of its compounds

36
Q

Cl2 + 2NaOH (cold and dilute) -> ?

A

NaCl (sodium chloride) + NaClO (sodium hypochlorite) + H2O

37
Q

Cl2 + NaOH (hot and concentrated) ->

A

NaCl + NaClO3 (sodium chlorate V) + H2O

38
Q

what is the trend in reducing agents down Group 7 halide salts?

A

increases, as ions get bigger it is easier for the outer electrons to be donated

39
Q

what is the test for halide ions?

A

nitric acid, then silver nitrate

40
Q

describe the method for halide ions test

A
  1. acidify the solution using dilute nitric acid

2. add a few drops of silver nitrate solution

41
Q

what does a white precipitate of silver halide show?

A

silver chloride

42
Q

what is the role of nitric acid in the silver nitrate halide test?

A

reacts with any carbonates present to prevent formation of silver carbonate

43
Q

what does a cream precipitate of silver halide show?

A

silver bromide

44
Q

what does a yellow precipitate of silver halide show?

A

silver iodide

45
Q

how are hydrogen halides produced?

A

sodium halide salts + phosphoric acid

46
Q

NaX +> H3PO4 -> ?

A

HX + NaH2PO4

47
Q

what is the observation when hydrogen halides are produced?

A

steamy fumes of the hydrogen halide, due to the halide meeting the air and dissolving in the moisture

48
Q

why is a downwards delivery tube used when producing hydrogen halides?

A

hydrogen halides are more dense than air and would settle at the bottom

49
Q

are hydrogen halides soluble in water, and if so, what do they form?

A

yes, acidic solutions

50
Q

describe the reaction of hydrogen halides with ammonia

A

HX + NH3 -> NH4X

white smoke

51
Q

how do you test for the presence of carbonate ions?(CO3 2-)

A
  1. add a dilute acid
  2. observe effervescence
  3. bubble gas through limewater to test for CO2 (cloudy)
52
Q

how do you test for the presence of a sulfate?

A
  1. acidified barium chloride (acid to cancel out carbonate)

2. if present - white precipitate forms (barium sulfate)

53
Q

how do you test for ammonium ions? (NH4+)

A
  1. add warm aqueous sodium hydroxide, forming ammonia

2. pungent smell, turns damp red litmus paper blue

Chemistry (7 decks)

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