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chemistry 2 > groups p1 > Flashcards

groups p1 Flashcards

1
Q

what is a common name given to group 2 metals?

A

alkaline earth metals

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2
Q

what is the most reactive metal of group2?

A

Barium

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3
Q

list 3 physical properties of group 2 metals

A

high melting and boiling points
low density metals
from colourless (white) compounds

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4
Q

the highest energy electrons of group 2 metals are in which subshell?

A

S subshell

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5
Q

does reactivity increase or decrease down group 2? why?

A

increases
electrons are lost more easily because larger atomic radius and more shielding

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6
Q

what happens to the first ionisation energy as you go down group 2? why?

A

decreases
number of filled electron shells increases down the group –> increased shielding
increased atomic radius –> weaker force between outer electrons
electron and nucleus –> less energy needed to remove electron

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7
Q

what type of reaction is the reaction between group 2 elements and oxygen?

A

redox

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8
Q

equation for the reaction of calcium and oxygen

A

2Ca(s) + O2(g) –> 2CaO(s)

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9
Q

what are the products when group 2 elements react with water?

A

hydroxide and hydrogen gas

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10
Q

which group 2 element doesn’t react with water?

A

beryllium

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11
Q

which group 2 element reacts very slowly with water?

A

magnesium

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12
Q

what type of reaction is the reaction between group 2 metal and water?

A

redox

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13
Q

equation of barium and water

A

Ba(s) + 2H2O(l) –> Ba(OH)2(aq) + H2(g)

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14
Q

what is oxidised adn what is reduced in a reaction between group 2 metal and water?

A

metal –> oxidised
one hydrogen atom from each water –> reduced

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15
Q

what are the products when a group 2 oxide reacts with a dilute acid?

A

salt and water

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16
Q

equation of calcium oxide and hydrochloric acid

A

CaO(s) + 2HCl(aq) –> CaCl2(s) + H2O(l)

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17
Q

what is formed when group 2 oxides react with water?

A

metal hydroxide

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18
Q

equation for the reaction between a group 2 oxide and water?

A

MO(s) + H2O(l) –> M(OH)2(aq)

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19
Q

what group 2 metal oxide is insoluble in water?

A

beryllium oxide

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20
Q

equation for the reaction between Mg(OH)2 and nitric acid

A

2HNO3(aq) + Mg(OH)2(aq) –> Mg(NO3)2(aq) + 2H2O(l)

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21
Q

what is the trend in hydroxide solubility down group 2?

A

increases
Mg(OH)2 is slightly soluble
Ba(OH)2 creates a strong alkaline solution

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22
Q

what is the trend in sulphate solubility down group 2?

A

decreases
BaSO4 - least soluble

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23
Q

what is the trend of thermal stability in g 1 carbonates?

A

g 1 carbonates do not decompose except for lithium - they don’t have a big enough charge density to polarise the carbonate ion (only form 1+ ions) - Li ion is small enough to have a polarising effect so therefore lithium carbonate can decompose

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24
Q

what is the trend of thermal stability in g 2 carbonates?

A

increases down the group because the cations get bigger so have less polarising effect distorting the carbonate ion less - C-O bond is not weakened as much - harder to break down

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25
Q

what is the trend of thermal stability in g 1 nitrates?

A

do not decompose expect lithium nitrate - lithium ion small enough to charge polarisation of the nitrate anion and thus weakening the N-O bond

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26
Q

what is the trend of thermal stability in g 2 nitrates?

A

increases - ions get larger and therefore have less charge density = less polarisation of nitrate anion and less weakening of the N-O bond

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27
Q

flame tests: Li

A

scarlet red

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28
Q

flame tests: Na

A

yellow

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29
Q

flame tests: K

A

lilac

30
Q

flame tests: Rb

A

red

31
Q

flame tests: Cs

A

blue

32
Q

flame tests: Mg

A

no flame colour

33
Q

flame tests: Ca

A

brick red

34
Q

flame tests: Sr

A

red

35
Q

flame tests: Ba

A

apple green

36
Q

how do you carry out a flame test?

A

1 use a nichrome wire
2 sterilise by dipping in conc HCl and heating in bunsen flame
3 dip wire in (powdered) solid and put in flame
4 observe colour

37
Q

how are the colours from the flame test formed?

A

the heat causes the electron to get excited and thus move to a higher energy level but at this higher level the electron is unstable so moves back down
as it moves from a higher to lower energy level energy is emitted in the form of visible light energy which is the colour you see

38
Q

which group are referred to as halogens?

A

group 7

39
Q

properties of the halogens?

A

low melting and boiling points, exist as diatomic molecules

40
Q

trend in boiling point down group 7?

A

increases
size of atom increases as more electron shells –> stronger London forces between molecules requiring more energy to break

41
Q

trend in reactivity down group 7?

A

decreases
atomic radius increases, electron shielding increases, ability to gain an electron and form 1- ions decreases

42
Q

trend in electronegativity down g 7?

A

decreases
atomic radii increases so there is reduced nuclear attraction between outermost electron and the nucleus

43
Q

trend in oxidising ability down g 7?

A

decreases (Cl strongest, I weakest)
Cl has fewest occupied electron shells, greatest force of attraction between outer electrons and nucleus and thus is the easiest to gain electrons and be reduced –> best oxidising agent

44
Q

trend in reducing ability of group 7?

A

increases (Cl- weakest, I- strongest)
I- has greatest atomic radius, weakest force of attraction between outer electrons and positive charge of nucleus and thus is the easiest to be oxidised and lose electrons –> best reducing agent

45
Q

what colour is chlorine in water? in cyclohexane?

A

pale green
pale green

46
Q

what colour is bromine in water? in cyclohexane?

A

orange
orange

47
Q

what colour is iodine in water? in cyclohexane?

A

brown
violet

48
Q

out of Cl-, Br-, I- which can be oxidised by chlorine?

A

Br- and I-

49
Q

equation of chlorine oxidising bromide ions in water and colour change

A

Cl2(aq) + 2Br-(aq) –> 2Cl-(aq) + Br2(aq)
yellow solution

50
Q

equation of chlorine oxidising iodide ions in cyclohexane and colour change

A

Cl2(aq) + 2I-(aq) –> 2Cl-(aq) + I2(aq)
purple solution

51
Q

out of Cl-, Br-, I- which can be oxidised by bromine?

A

I- ions

52
Q

equation for bromine oxidising iodide ions in water and colour change

A

Br2(aq) + 2I-(aq) –> 2Br-(aq) + I2(aq)
brown solution

53
Q

out of Cl-, Br-, I- which can be oxidised by iodine?

A

does not oxidise Cl- or Br-

54
Q

disproportionation

A

the oxidation and reduction of the same element in a redox reaction

55
Q

what is the equation of Cl2 with water?

A

Cl2(g) + H2O(l) –> HClO(aq) + HCl(aq)
disproportionation reaction

56
Q

why is chlorine added to drinking water?

A

kills the bacteria in the water and makes it safer to drink

57
Q

what are the two forms of the chlorate ion?

A

ClO^- chlorate (I)
ClO3^- chlorate (V)

58
Q

equation for forming bleach? conditions?

A

(NaClO is bleach)
Cl2(aq) + 2NaOH(aq) –> NaCl(aq) + NaClO(aq) + H2O(l)
cold dilute alkali

59
Q

equation of chlorine and hot dilute NaOH

A

3Cl2(aq) + 6NaOH(aq) –> 5NaCl(aq) + NaClO3(aq) + 3H2O
disproportionation

60
Q

how do you test for halide ions? results?

A

acidified AgNO3
Cl- = white ppt
Br- = cream ppt
I- = yellow ppt

61
Q

when testing for halide ions why do you add HNO3 not HCl?

A

to remove CO3 2-
adding HCl would add Cl- ions, giving a false positive result

62
Q

what happens to each of the silver halide precipitates when dilute/conc NH3 is added?

A

AgCl- dissolves in both dilute and conc
AgBr- dissolves in conc
AgI- does not dissolve

63
Q

trend in oxidising ability down g 7?

A

decreases down group (Cl best, I worst)
Cl has fewest occupied electron shells therefore greatest attraction between outer electrons and nucleus, easiest to gain electrons and be reduced

64
Q

trend in reducing ability down group 7?

A

increases down group (Cl- worst, I- best)
I- has most occupied electron shells so outer electrons are further from the nucleus, weakest force of attraction between outer electrons and positive charge of nucleus –> easiest to be oxidised and lose electrons

65
Q

what products are formed when I- reduces H2SO4?

A

H2SO4 + 2I- –> SO4 2- + 2HI
H2SO4 + 2H+ + 2I- –> SO2 + I2 + 2H2O (SO2 is a choking gas with a pungent odour)
H2SO4 + 6H+ + 6I- –> S + 3I2 + 4H2O (S is a yellow solid)
H2SO4 + 8H+ + 8I- –> H2S + 4I2 + 4H2O (H2S smells of rotten eggs)

66
Q

products of Br- and H2SO4?

A

HBr and SO2

67
Q

does Cl- reduce H2SO4?

A

no - only HCl is formed

68
Q

how can you test for carbonate ions (CO3 2-)?

A

add strong acid
collect the gas produced
pass through lime water

limewater turns cloudy and effervescence is positive

CO3 2-(aq) + 2H+ (aq) –> H2O(aq) + CO2(g)

69
Q

how can you test for sulfate ions (SO4 2-)?

A

add dilute HCl and barium chloride/nitrate

white ppt of barium sulfate is produced

Ba 2+(aq) + SO4 2-(aq) –> BaSO4(s)

70
Q

what do you use to test for halide ions?

A

acidified AgNO3

71
Q

when testing for carbonate, sulfate and halide ions, in which order should the tests be carried out and why?

A

1 carbonate
2 sulfate
3 halide

barium ions form insoluble ppt of BaCO3 and silver ions form insoluble ppt of Ag2SO4

72
Q

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

A

add NaOH to the sample and warm it
test the gas produced with red litmus paper

red litmus paper turns blue, pungent smell

NH4 +(aq) + OH-(aq) –> NH3(aq) + H2O(aq)

chemistry 2 (21 decks)

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