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Group 7 Flashcards

1
Q

Explain the trend in electronegativity as you go down group 7.

A

Electronegativity decreases as you go down group 7 because size of atoms increase. Their atomic radius is greater and there is more shielding. Therefore the greater nuclear charge has no great effect.

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2
Q

Explain the trend in boiling point as you go down group 7.

A

As you go down the size of each atom increases and therefore there are more van der waals forces. Therefore more energy is required to break the bonds.

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3
Q

What type of molecules are halogens ?

A

Simple, diatomic covalent molecules.

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4
Q

What colour are each of the halogens in pure form ?

A

Fluorine - pale yellow has
Chlorine - pale green has
Bromine - dark red liquid
Iodine - grey solid

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5
Q

Outline the physical properties of each of the halogens in non-polar solvents.

A

Fluorine- reacts with solvents
Chlorine - pale green solution
Bromine - orange solution
Iodine - purple solution.

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6
Q

Outline the physical properties of the halogen in water.

A

Fluorine - reacts with water
Chlorine- pale green solution
Bromine - orange solution
Iodine - insoluble. But forms a brown solution if excess KCl is present.

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7
Q

Describe the physical properties of astatine at room temperature.

A

Black solid

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8
Q

Why do we rarely experiment with astatine ?

A

It is highly radioactive so is unstable.

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9
Q

Describe the trends in ionisation energy as you go down group 7.

A

Ionisation energy decreases. The atomic radius of each atom increases and there is more shielding so the attraction of the nucleus to the outer electrons is less.

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10
Q

Describe the polarity of halogens ?

A

Non-polar

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11
Q

What property of halogens means they dissolve well in nonpolar solvents.

A

Halogens are non-polar

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12
Q

Describe the trends in oxidising power of halogens as you go down group 7.

A

Oxidising power decreases. It is therefore more difficult for iodine to accept electrons than fluorine. The smaller atoms can attract electrons more easily with their nuclear charge as they have less shielding.

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13
Q

What colour are halide ions ?

A

Colourless

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14
Q

When can a displacement reaction with halogens not occur.

A

When the diatomic halogen molecules is lower in the group (less reactive) than tha halide ion.

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15
Q

What charge do halide ions have ??

A

-1

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16
Q

Describe the trend in reducing ability of halide ions as you go down the group.

A

As you go down group 7 reducing ability increases because atomic radius of each atom increasss so the electron being lost isn’t held as strongly to the nuclear charge and can be easily lost.

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17
Q

What affect does sodium chloride have on concentrated sulphuric acid ??

A

No reactions can occur because chlorine has a low reducing power.

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18
Q

What affect does sodium bromine have on concentrated sulphuric acid ??

A

Bromine can reduce sulphuric acid to sulphur dioxide.

You get: Br2, SO2

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19
Q

What affect does sodium iodide have on concentrated sulphuric acid ??

A

Sodium iodidide can reduce the sulphuric acid to sulphur dioxide, hydrogen sulphide and solid sulphur because it can donate electrons easily.

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20
Q

What substance is used to identify halides ?

A

Acidified silver nitrate.

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21
Q

What colour precipitate does silver chloride form in water and why ?

A

White

It has a low solubility in water

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22
Q

What are the products of each halide ion in acidified silver nitrate ?

A

Fluoride - colourless
Chloride - white
Bromide - yellow
Iodide -Colourless

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23
Q

Describe the products form for each halide ion in dilute NH3

A

Chloride - soluble
Bromide - partly soluble
Iodide - insoluble

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24
Q

Describe the products form for each halide ion in concentrated NH3

A

Chloride - soluble
Bromide - soluble
Iodide - insoluble

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25
Why can’t hydrochloride acid be used to identify halide ions ?
A white precipitate will be formed giving a false positive.
26
Why is the silver nitrate solution acidified.
It allows an acid base faction which removes carbonate ions which could interfere with the silver nitrate test.
27
Why does HF have an exceptionally high boiling point ?
Because it has hydrogen intermolecular bonding.
28
What are the uses of chlorine ?
Kills bacteria in drinking water and swimming pools. Bleach
29
Write the reaction of chlorine with water.
Cl2(g) + H2O(l) — HClO(aq) + HCl(aq)
30
What type of reaction is the reaction of chlorine with water.
Disporportiination
31
What is chloric1acid used for ?
Oxidising agent which sterilised water.
32
Why can chlorine gas be used to sterilise water despite being toxic.
Used in low dosage.
33
What is the equation for chlorine reacting with an alkali ?? (Sodium hydroxide )
Cl2 (g) + 2NaOH(an) - NaClO(an) + NaCl(an) +H2O(l)
34
What type of reaction is the equation for chlorine reacting with an alkali ?? (Sodium hydroxide )
Disproportionation
35
What is sodium chlorate 1 used for ?
An oxidising agent is the active ingredient in household bleach.
36
Write a half-equation for the reaction of MnO2 in acid to form Mn2+ ions and water as the only products.
MnO2 +4H+ +2e- - MN2+ + 2H2O
37
Write an equation for the reaction of solid potassium chloride with concentrated sulphuric acid.
H2SO4 + Cl- - KHSO4 + HCl
38
Explain why chloride ions are weaker reducing Agnes than bromide ions.
They are smaller and therefore the nuclear charge has a greater effect to attract the electrons.
39
When a solution of this sodium halide is mixed with silver nitrate solution, no precipitate is formed. Write the formula of the sodium halide.
NaF
40
This sodium halide is a white solid that reactions with concentrated sulphuric acid to give a brown gas.
NaBr
41
When his solid sodium halide reacts with concentrated sulphuric acid, the reaction mixture remains white and steamy fumes are given off.
NaF
42
A colourless aqueous solution of this sodium halide rreacts with orange bromine water to give a dark brown solution. What is the formula of this halide.
NaI
43
Write the equation equation for chlorine reacting with cold water.
Cl2 + H2P - HCl + HClO
44
Write the simplest ionic equation for the reaction of chlorine with bromide ions.
2Br- + Cl2 - 2Cl- + Br2
45
Give one reason why the silver nitrate solution was acidified.
Reacts with ions and carbonates that would interfere with the test.
46
Why can fluorine ions not be identified ?
Thy are highly reactive and form no visible precipitate.
47
Write an equation for the reaction when chlorine gas is bubbled into an aqueous solution of potassium iodide.
Cl2(g) + 2kI - I2 +2KCl | Brown solution would form
48
Describe what you would observe when aqueous silver nitrate followed by dilute aqueous ammonia is added to separate aqueous solutions of sodium chloride and sodium bromide.
Sodium chloride would have a white precipitate which would teen fully dissolve. Sodium bromide would have a cream precipitate which would not dissolve.
49
State th trend in oxidising abilities of the elements down group 7 from chlorine to iodide. Explain how this trend can be shown by displacement reactions between halogens and halide ions in aqueous solutions.
Oxidising ability decreases because size of atoms increases therefore there is more shielding and the ability of the nucleus to attract electrons decreases.
50
Explain why bromine does not react with aqueous chloride ions.
It is less reactive than chlorine.
51
Write an equation to show how solid potassium fluoride reacts with concentrated sulphuric acid.
2H2SO4 + 2Br- - SO2 + Br2 + SO42- + 2H2O
52
Identify the halogen that is the strongest oxidising agent.
Fluorine
53
What substance is used to identify halides ?
Acidified silver nitrate.
54
What colour precipitate does silver chloride form in water and why ?
White | It has a low solubility in water
55
What are the products of each halide ion in acidified silver nitrate ?
Fluoride - colourless Chloride - white Bromide - yellow Iodide -Colourless
56
Describe the products form for each halide ion in dilute NH3
Chloride - soluble Bromide - partly soluble Iodide - insoluble
57
Describe the products form for each halide ion in concentrated NH3
Chloride - soluble Bromide - soluble Iodide - insoluble
58
Why can’t hydrochloride acid be used to identify halide ions ?
A white precipitate will be formed giving a false positive.
59
Why is the silver nitrate solution acidified.
It allows an acid base faction which removes carbonate ions which could interfere with the silver nitrate test.
60
Why does HF have an exceptionally high boiling point ?
Because it has hydrogen intermolecular bonding.
61
What are the uses of chlorine ?
Kills bacteria in drinking water and swimming pools. Bleach
62
Write the reaction of chlorine with water.
Cl2(g) + H2O(l) — HClO(aq) + HCl(aq)
63
What type of reaction is the reaction of chlorine with water.
Disporportiination
64
What is chloric1acid used for ?
Oxidising agent which sterilised water.
65
Why can chlorine gas be used to sterilise water despite being toxic.
Used in low dosage.
66
What is the equation for chlorine reacting with an alkali ?? (Sodium hydroxide )
Cl2 (g) + 2NaOH(an) - NaClO(an) + NaCl(an) +H2O(l)
67
What type of reaction is the equation for chlorine reacting with an alkali ?? (Sodium hydroxide )
Disproportionation
68
What is sodium chlorate 1 used for ?
An oxidising agent is the active ingredient in household bleach.
69
Write a half-equation for the reaction of MnO2 in acid to form Mn2+ ions and water as the only products.
MnO2 +4H+ +2e- - MN2+ + 2H2O
70
Write an equation for the reaction of solid potassium chloride with concentrated sulphuric acid.
H2SO4 + Cl- - KHSO4 + HCl
71
Explain why chloride ions are weaker reducing Agnes than bromide ions.
They are smaller and therefore the nuclear charge has a greater effect to attract the electrons.
72
When a solution of this sodium halide is mixed with silver nitrate solution, no precipitate is formed. Write the formula of the sodium halide.
NaF
73
This sodium halide is a white solid that reactions with concentrated sulphuric acid to give a brown gas.
NaBr
74
When his solid sodium halide reacts with concentrated sulphuric acid, the reaction mixture remains white and steamy fumes are given off.
NaF
75
A colourless aqueous solution of this sodium halide rreacts with orange bromine water to give a dark brown solution. What is the formula of this halide.
NaI
76
Write the equation equation for chlorine reacting with cold water.
Cl2 + H2P - HCl + HClO
77
Write the simplest ionic equation for the reaction of chlorine with bromide ions.
2Br- + Cl2 - 2Cl- + Br2
78
Give one reason why the silver nitrate solution was acidified.
Reacts with ions and carbonates that would interfere with the test.
79
Why can fluorine ions not be identified ?
Thy are highly reactive and form no visible precipitate.
80
Write an equation for the reaction when chlorine gas is bubbled into an aqueous solution of potassium iodide.
Cl2(g) + 2kI - I2 +2KCl | Brown solution would form
81
Describe what you would observe when aqueous silver nitrate followed by dilute aqueous ammonia is added to separate aqueous solutions of sodium chloride and sodium bromide.
Sodium chloride would have a white precipitate which would teen fully dissolve. Sodium bromide would have a cream precipitate which would not dissolve.
82
State th trend in oxidising abilities of the elements down group 7 from chlorine to iodide. Explain how this trend can be shown by displacement reactions between halogens and halide ions in aqueous solutions.
Oxidising ability decreases because size of atoms increases therefore there is more shielding and the ability of the nucleus to attract electrons decreases.
83
Explain why bromine does not react with aqueous chloride ions.
It is less reactive than chlorine.
84
Write an equation to show how solid potassium fluoride reacts with concentrated sulphuric acid.
2H2SO4 + 2Br- - SO2 + Br2 + SO42- + 2H2O
85
Identify the halogen that is the strongest oxidising agent.
Fluorine
86
State 2 factors which alter the solubility of different sulphates ?
Hydration energy and the energy required to break down the lattice.

Chemistry (27 decks)

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