Topic 4 - Inorganic Chemistry and the Periodic Table Flashcards
(119 cards)
1
Q
what is the trend in ionisation energy as you go down group 2?
A
first ionisation energy decreases down the group
2
Q
what is ionisation energy?
A
the energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous positive ions eg Na(g) → Na⁺(g) + e⁻
- it is a measure of the strength of electrostatic attraction between the outer electron and the nucleus
3
Q
what is the reason for the trend in ionisation energy in group 2?
A
- The outermost electrons are held more weakly because they are successively further from the nucleus in additional shells.
- the outer shell electrons become more shielded from the attraction of the nucleus by the repulsive force of inner shell electrons
4
Q
what is the trend in reactivity as you go down group 2?
A
reactivity increases
5
Q
what is the reason for the trend in reactivity as you go down group 2?
A
the atomic radii increase
there is more shielding.
The nuclear attraction decreases and it is easier to remove (outer) electrons and so cations form more easily
6
Q
what is formed when a group 2 metal reacts with water?
A
a metal hydroxide and hydrogen gas
M(s) + H2O(l) ➔ M(OH)2(aq) + H2(g)
7
Q
what is the charge on an ion from group 2?
A
2+
8
Q
what is the reactivity when Beryllium reacts with water?
A
no reaction
9
Q
what is the reactivity when Magnesium reacts with water and what is produced?
A
magnesium hydroxide
Mg + 2 H2O ➔ Mg(OH)2 + H2
very slow reaction
10
Q
what is produced when magnesium reacts with steam?
A
magnesium oxide and hydrogen
Mg (s) + H2O (g) ➔ MgO (s) + H2 (g)
11
Q
what is the reactivity of Calcium with water?
A
there is a steady rate of reaction
12
Q
what is the reactivity of Strontium with water?
A
the reaction happens fairly quickly
13
Q
what is the reactivity of Barium with water?
A
there is a rapid rate of reaction
14
Q
what pH is the water after a group 2 reaction takes place?
A
alkaline due to the hydroxide ions produced
15
Q
what are some observations from the reaction between a group 2 metal and water
A
-fizzing, (more vigorous down group)
-the metal dissolving, (faster down group)
-the solution heating up (more down group)
-and with calcium a white precipitate appearing (less precipitate forms down group)
16
Q
what is formed when a group 2 metal burns in oxygen gas?
A
a solid white oxide
17
Q
what is produced when a group 2 metal reacts with chlorine gas?
A
a solid white chloride
18
Q
what is trend of solubility in group 2 metal hydroxides?
A
they become more soluble as you go down the group
19
Q
what is trend of solubility in group 2 metals sulfates?
A
they become less soluble down the group
20
Q
when group 2 metal oxides react with water what is formed?
A
metal hydroxides, that dissolve in water
21
Q
what is the trend in pH of the resulting solution after group 2m oxides react with water?
A
pH increases down the group as the solubility of the hydroxides increases
22
Q
which group 2 oxide is an exception to the trend in pH and why?
A
Magnesium oxide (MgO) – it reacts slowly and has low solubility, so it forms a less alkaline solution.
23
Q
what do group 2 metal hydroxides (M(OH)2) react with to form salt and water?
A
dilute acids eg hydrochloric acid - It neutralises the acid
24
Q
what is a property of group 1 carbonates and what is an exception to this?
A
they are very stable and don’t decompose with bunsen burner heating
an exception is lithium carbonate which decomposes to form lithium oxide and carbon dioxide
25
what do group 1 nitrates decompose to and what is an exception to this?
nitrites and oxygen
eg 2NaNO3(s) ➔ 2NaNO2(s) + O2(g)
an exception is lithium nitrate which decomposes to lithium oxide, nitrogen dioxide and oxygen
26
what do group 2 compounds decompose to?
oxides and carbon dioxide
eg CaCO3(s) ➔ CaO(s) + CO2(g)
27
what do group 2 nitrates decompose to?
oxides, nitrogen dioxide and oxygen
28
what do group 1 carbonates decompose to?
trick question - they don't decompose -stop guessing
29
what is the trend in thermal stability of carbonates and nitrates as you move down both group 1 and 2?
the thermal stability increases
30
what is ion polarisation?
the distortion of an anions electron cloud by a nearby cation
31
what is polarising power?
a cations ability to distort an anions electron cloud
32
what is the trend in the size of cations as you move down the group?
cations become larger
33
how does the size of the cation affect thermal stability?
larger cations have lower charge density resulting in lower polarising power, causing less anion distortion
less distortion leads to stronger C-O and N-O bonds increasing stability
34
how does cation charge affect thermal stability?
group 2 cations (+2) have a higher charge than group 1 cations (+1), higher charge results in greater polarising power, this makes group 2 compounds less stable than group 1 compounds
So, compounds with higher-charged cations tend to be less thermally stable.
35
how can you test the thermal stability of group 2 carbonates?
measure the time taken to produce enough CO2 gas to turn limewater cloudy when it is heated
36
how can you test the thermal stability of group 1 nitrates?
measure the time taken to produce enough O2 gas to relight a glowing splint when it is heated
37
how can you test the thermal stability of group 2 nitrates?
in a fume cupboard measure the time taken to produce brown NO2 gas when it is heated
38
give 2 ways in which you can collect the gas given off?
using a gas syringe or a test tube upturned in a beaker of water - displacement of water
39
describe a flame test procedure
1. mix a small amount of the compound with a few drops of hydrochloric acid
2. clean a platinum or nichrome wire by heating it in a hot bunsen flame
3. dip the wire into the compound/acid mixture
4. hold the wire in a hot flame and observe the colour produced
40
what colour flame does lithium produced?
red
41
what colour flame does sodium produce?
orange/yellow
42
what colour flame does potassium give off?
lilac
43
what colour flame does rubidium give off?
red
44
what colour flame does caesium give off?
blue
45
what colour flame does calcium produce?
orange-red
46
what colour flame does strontium produce?
crimson
47
what colour flame does barium produce?
green
48
how do group 1 and 2 compounds form characteristic flame colours?
In a flame test the heat causes the electron to move to a higher energy level.
The electron is unstable at the higher energy level and so drops back down. As it drops back down from the higher to a lower energy level, energy is emitted in the form of visible light energy with the wavelength of the observed light
49
what colour flame does magnesium produce?
another trick question, you're really bad at these - magnesium does not have a flame colour as the energy emitted is of a wavelength outside the visible spectrum - I bet you wish your waist was like that huh
50
which group are the halogens a part of and name the first 4
group 7
fluorine
chlorine
bromine
iodine
51
why are halogens diatomic?
they are highly active non-metals so they form diatomic molecules with one covalent bond between 2 atoms eg F2
52
what is the appearance of fluorine at room temp?
pale yellow gas
53
what is the appearance of chlorine at room temp?
green gas
54
what is the appearance of bromine at room temp?
red-brown liquid
55
what is the appearance of iodine at room temp?
grey solid
56
what is the trend in boiling and melting points as you go down group 7?
they increase
57
what's the reason for the trend of melting and boiling points in group 7 as you go down?
The molecules become larger in size and relative mass.
This allows for stronger induced dipole-dipole forces to develop between molecules.
These stronger intermolecular forces require increasing amounts of energy to overcome.
So the the halogens melt and boil at higher temperatures down the group
58
what is the trend in electronegativity as you go down group 7?
it decreases
59
what is the reason for the trend in electronegativity as you go down group 7?
the atomic radii increases due to the increasing number of shells. The nucleus is therefore less able to attract the bonding pair of electrons
therefore electronegativity decreases down the group
shielding - Inner electron shells reduce the atom’s ability to attract electrons
60
what is electronegativity?
refers to the tendency of an atom to attract a bonding pair of electrons
61
what is the charge of halide ions?
1-
62
what is the reaction when the halogen gains the electron?
reduction reaction as its oxidation number decreases from 0 to -1
63
what type of agents are halogens?
As the halogen gains an electron, it causes another substance to be oxidised - so halogens act as oxidising agents
64
what is the trend in reactivity as you go down group 7?
the reactivity decreases as you go down the group?
65
what is the reason for the trend in reactivity of group 7 as you go down the group?
Atomic radius increases down the group as more electron shells are added.
The increasing size leads to the outer electrons being farther from the positive nucleus.
The outer electrons also experience more shielding from inner electron shells.
The electrostatic attraction between the outer electrons and nucleus gets progressively weaker.
The increase in atomic radius and shielding outweigh the increase in nuclear charge so it becomes harder for larger halogens to attract the electron needed to form a negative ion.
66
What happens when a halogen with stronger oxidising power reacts with a halide compound of a weaker halogen?
A more reactive halogen (stronger oxidising agent) will displace a less reactive halogen (weaker oxidising agent) from its halide compound in solution.
67
what does oxidising power of halogens refer to?
their ability to take electrons from other substances to form halide ions
68
which halogen is the strongest oxidising agent?
fluorine
69
which halogen is the strongest oxidising agent?
iodine
70
What is a halogen displacement reaction?
It’s a reaction where a more reactive halogen displaces a less reactive halogen from one of its compounds
71
What is the general rule for halogen displacement?
halogen higher in the group will displace one that’s lower from a halide solution.
72
What happens when Cl₂ is added to a solution of Br⁻?
Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂
Chlorine displaces bromine because it is a stronger oxidising agent.
73
what colour is chorine when in an organic solvent?
pale green
73
Why is an organic solvent (like cyclohexane) added in halogen displacement reactions?
halogens are more soluble in organic solvents and show distinctive colours, helping to visually confirm with halogen was displaced
74
what colour is the organic layer when bromine is in an organic solvent?
orange
75
what colour is the organic layer when iodine is in an organic solvent?
violet
76
what type of reaction is a displacement reaction?
a redox reaction because one species is oxidised and the other is reduced.
77
In the reaction Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂, which element is oxidised and which is reduced?
Cl₂ is reduced (gains electrons)
Br⁻ is oxidised (loses electrons)
78
What does a yellow colour in the aqueous solution indicate during a displacement reaction?
Bromide ions (Br⁻) have been displaced, forming bromine (Br₂).
79
What does an orange/brown colour in the aqueous solution indicate?
Iodide ions (I⁻) have been displaced, forming iodine (I₂).
80
What does it mean if the solution remains colourless after adding a halogen?
No displacement reaction occurred — the halogen added is less reactive than the halide ion
81
in all reactions where halogens are reacting with metals which is being oxidised?
the metals are being oxidised
82
what is formed when halogens react with group 1 and 2 metals?
halide salts - metal halides
83
what are the IUPAC names for these compounds
NaClO
NaClO3
K2SO4
K2SO3?
sodium chlorate(I)
sodium chlorate(V)
potassium sulfate(VI)
potassium sulfate(IV)
84
in all reactions where halogens are reacting with metals which is being reduced?
the halogen
85
What is the chemical equation for the reaction between chlorine and water?
Cl₂ + H₂O ⇌ HCl + HClO
86
What are the oxidation numbers of chlorine in Cl₂, HCl, and HClO in the reaction Cl₂ + H₂O ⇌ HCl + HClO?
Cl₂ = 0
In HCl = –1 (reduced)
In HClO = +1 (oxidised)
87
Why is the reaction of chlorine with water a disproportionation reaction?
Because one chlorine atom is reduced to –1 (in HCl) and the other is oxidised to +1 (in HClO)
88
What is the use of HClO (chloric(I) acid) formed in this reaction?
It is a powerful disinfectant used in water treatment to kill bacteria.
89
what colour are the halogens when they reacts with cold sodium hydroxide (NaOH) in aqueous solutions?
the halogen will fade to colourless
90
what does the disproportionation reaction of chlorine with NaOH form?
mixture of NaCl and NaClO - bleach
used to disinfect/kill bacteria
91
what happens when a halogen reacts with a hot alkali (eg NaOH)
the halogen being oxidised goes to a higher oxidation state
92
what is formed in the disproportionation reaction of chlorine with NaOH?
chlorate (V) - NaClO3
93
what are halide ions?
negatively charged ionic forms of halogens, they have a 1- charge and end with -ide
eg chloride
94
what is formed when halide ions react with concentrated sulphuric acid?
hydrogen halide gases initially
95
what is the reaction between fluoride and sulphuric acid and what observations are made?
NaF(s) + H2SO4(aq) ➔ NaHSO4(aq) + HF(g)
misty white fumes of HF are seen
96
what is the reaction between chloride and sulphuric acid and what observations are made?
NaCl(s) + H2SO4(aq) ➔ NaHSO4(aq) + HCl(g)
misty white fumes of HCl are seen
97
what is the trend in reducing power of halide ions as you go down group 7?
the reducing power increases as you go down group 7
98
explain the trend of reducing power of halide ions as you go down group 7
ionic radius increases down group 7 as more shells are added
the increasing ionic radius leads to the outer electrons being further from the positive nucleus
the outer electrons experience more shielding from inner electron shells
the electrostatic attraction between the outer electrons and nucleus gets progressively weaker
the increase in ionic radius and shielding outweigh the increase in nuclei charge so it becomes easier for larger halide ions to lose electrons and become oxidised
therefore fluoride is the weakest reducing agent and iodide is the strongest
99
can fluoride and chloride have further redox reactions, if yes what is the formula and what observations are made?
no as they have low reducing number
100
what is the reaction between bromide and sulfuric acid and what observations are made?
NaBr(s) + H2SO4(aq) ➔ NaHSO4(aq) + HBr(g)
misty fumes of HBr gas are initially produced
101
can bromide ions produce further redox reactions? if yes what is the formula and what observations are made?
bromide ions reduce H2SO4 to SO2
2HBr(g) + H2SO4(aq) ➔ Br2(g) + SO2(g) + 2H2O(l)
orange bromine vapour and choking SO2 gas is observed
102
what is the reaction between iodide and sulfuric acid and what observations are made?
NaI(s) + H2SO4(aq) ➔ NaHSO4(aq) + HI(g)
misty fumes of HI gas are initially produced
103
can iodide ions produce further redox reactions? if yes what is the formula and what observations are made?
iodide ions reduce H2SO4 to SO2
2HI(g) + H2SO4(aq) ➔ I2(g) + SO2(g) + 2H2O(l)
violet iodine vapour and choking SO2 gas are observed
iodide ions can then reduce SO2 further to produce H2S gas
6HI(g) + SO2(g) ➔ H2S(g) + 3I2(s) + 2H2O(l)
violet iodine vapour and the rotten egg smell of H2S gas are observed
104
what can be seen during the reduction reaction between sulfuric acid and iodide?
solid yellow sulfur and the oxidation number of sulfur passes through 0
105
what is used to test for the presence of halide ions in a sample?
aqueous silver nitrate (AgNO3)
106
what is the method for testing for the presence of halide solutions in a sample?
1. add dilute nitric acid to the sample to remove any ions eg carbonates that may interfere by also forming precipitates with silver nitrate, confounding the results
2. add silver nitrate solution, silver ions react with halide ions to form silver halide precipitates
3. observe precipitate colour to identify which halide ion is present
107
what are the precipitate colours formed for chloride, bromide and iodide when they react with aqueous silver nitrate?
chloride (Cl-) - white
bromide (Br-) - cream
iodide (I-) - yellow
108
when testing for the presence of halide ions in a solution the precipitates formed have similar colours, what ca be added to confirm the identity of the halide present?
add excess ammonia solution - silver halide have different solubilities in dilute and concentrated ammonia solution
109
what effect does dilute NH3 (aq) and concentrated NH3 (aq) have on chloride?
dilute NH3 - dissolves
concentrated NH3 - dissolves
110
what effect does dilute NH3 (aq) and concentrated NH3 (aq) have on bromide?
dilute NH3 - remains insoluble
concentrated NH3 - dissolves
111
what effect does dilute NH3 (aq) and concentrated NH3 (aq) have on iodide
dilute NH3 - remains insoluble
concentrated NH3 - remains insoluble
112
how are hydrogen halides produced?
reacting solid sodium halide salts with phosphoric acid
NaCl(s) + H3PO4(l) ➔ NaH2PO4(s) + HCl(g)
113
what happens when hydrogen halides are exposed to moist air or water vapour?
hydrogen halides form misty fumes due to the formation of tiny droplets of the aqueous acid solution
114
describe the reaction of hydrogen halides with water
these reactions produce strong acids as the hydrogen halides fully dissociate in water
HX(g) + H2O(l) ➔ H3O+(aq) + X-(aq)
For example:
HCl(g) + H2O(l) ➔ H3O+(aq) + Cl-(aq) (hydrochloric acid)
115
describe the reaction of hydrogen halides with ammonia
hydrogen halides reaction with ammonia gas to form ammonium halide salts - this is an acid-base reaction producing white fumes of the solid ammonium halide salt
these reactions occur readily due to the strong affinity between the acidic hydrogen halides and the basic ammonia molecule
116
how do you test for the presence of carbonate (CO3^2-) or hydrogencarbonate (HCO3-) ions?
1. add dilute nitric acid (HNO3) a drop at a time to a sample containing an unknown ion
2. carefully observe for effervescence -bubbles/fizz - caused by bubbles of CO2 gas being evolved
3. confirm the presence of CO2 by passing bubbles of the gas through limewater (calcium hydroxide solution), in a connecting test tube, if CO2 is present the limewater will turn cloudy due to the formation of a whiter calcium carbonate precipitate confirming the original presence of carbonate ions in the sample
117
how do you test for the presence of sulphate ions (SO4^2-) ions?
1. add dilute nitric acid (HNO3) a drop at a time to sample containing an unknown ion
2. add a few drops of a solution containing aqueous Ba2+ ions, such as barium chloride (BaCl2) or barium nitrate (Ba(NO3)2) to the sample
3. observe carefully for the formation of a white precipitate of barium sulphate (BaSO4)
118
how do you test for the presence of ammonium ions (NH4+)?
1. add sodium hydroxide solution a drop at a time to a sample containing ammonium ions
2. gently warm the mixture. they hydroxide ions react with ammonium ions to produce ammonia gas
3. moisten a piece of red litmus paper and hod over test tube the paper will turn blue if ammonia gas is present confirming that ammonium ions were originally present in the sample
