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Group 7 Flashcards

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1
Q

How do group 7 elements exist?

A

As diatomic molecules

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2
Q

How many electrons do group 7 elements have in their p orbitals?

A

nP5

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3
Q

Trend in boiling point down the group

A

Increases

  • increased London forces due to more electrons
  • more energy required to separate the molecules
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4
Q

Physical state of Chlorine at room temperature

A

Gas (green)

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5
Q

Physical state of Bromine at room temperature

A

Liquid (red-brown)

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6
Q

Physical state of Iodine at room temperature

A

Solid (grey/black)

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7
Q

Trend in electronegativity going down the group

A

Decreases down the group

  • increased distance from nucleus
  • more shielding

These two factors cancel out the effect of increased nuclear charge

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8
Q

Trend in atomic radius going down group 7

A

Increases

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9
Q

Trend in ionic size going down the group

How does this compare with the size of the atoms of the elements?

A

Increases

Ions are larger due to increased number of electrons
This means the force of attraction from the nucleus is spread more thinly so electrons move further out

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10
Q

Trend in oxidising ability going down the group

Explain the trend

A

Decreases

  • less attraction from the nucleus due to increased distance
  • more shielding
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11
Q

Which halogen out of Cl, Br and I is best at displacing other halogens?

Give the order of displacement

A

Cl

Cl > Br > I

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12
Q

Give the equation for the oxidation of bromide ions using chlorine

A

Cl2 + 2Br- –> Br2 + 2Cl-

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13
Q

Give the equation of bromine oxidising Iodide ions to iodine

A

Br2 + 2I- –> I2 + 2Br-

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14
Q

Give the equation for the reaction of chlorine with sodium bromide

A

Cl2 + 2NaBr –> 2NaCl + Br2

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15
Q

Give the equation for the reaction of chlorine with water and the results of testing the reaction with litmus paper

A

Cl2(g) + H20(l) ⇌ HCl(aq) + HOCl(aq)

Litmus would turn red, due to the HCl, and then be bleached white by the HOCl

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16
Q

Give a use of NaClO

A

Active ingredient in household bleach

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17
Q

Equation for the reaction of chlorine with cool, dilute aqueous sodium hydroxide

What type of reaction is it?

Study These Flashcards
A

Cl2 + 2NaOH –> NaCl + NaClO +H2O

Disproportionation as the chlorine is both oxidised and reduced

18
Q

Give another name for sodium chlorate(I)

Study These Flashcards
A

Sodium hypochlorite

19
Q

Give the equation of the reaction between chlorine with hot, concentrated sodium hydroxide solution

Study These Flashcards
A

3Cl2 + 6NaOH –> 5NaCl + NaClO3 + 3H2O

20
Q

What is the name of NaClO3?

Study These Flashcards
A

Sodium chlorate(V)

21
Q

Which halide ion is the most reducing?

Why?

Study These Flashcards
A

I-

-as ionic radius increases, it becomes easier to remove outer electrons

22
Q

Describe the test for halides using silver nitrate

Study These Flashcards
A
  • Add dilute nitric acid to the sample containing the halide
  • Add a few drops of silver nitrate solution
  • Observe colour of precipitate of silver halide
23
Q

Describe what you would do to precipitates formed from adding silver nitrate to solutions containing halides. Give the results

Study These Flashcards
A
  • Add dilute ammonia solution
  • If precipitate still exists, add concentrated ammonia solution

Silver chloride - dissolves in both dilute and concentrated ammonia solution

Silver bromide - dissolves in concentrated ammonia solution but not in dilute

Silver Iodide - doesn’t dissolve in either

24
Q

Give the colours of the precipitates formed from the three halides reacting with silver nitrate solution

Study These Flashcards
A

Chloride - White ppt

Bromide - Cream ppt

Iodide - Yellow ppt

25
What is the complex formed when a silver halide is dissolved in ammonia?
[Ag(NH3)2]+ Colourless diammine complex
26
Write the equation for the partial ionisation of sulfuric acid
H2SO4 ⇌ H+ + SO4 2-
27
Three possible reduction products of sulfuric acid
Sulfur dioxide - SO2 Sulfur - S Hydrogen sulfide - H2S
28
What happens when you add concentrated sulfuric acid to the halides?
- Sulfuric acid displaces the weaker acids HCl, HBr and HI from their salts - Hydrogen halides all fume in moist air - Sulfuric acid is reduced to lower oxidation states of Sulfur the further you go down the group
29
What are the products when concentrated sulfuric acid is added to a solution of NaCl? Give the equation and any observations
HCl produced White, misty fumes given off NaHSO4 also produced NaCl + H2SO4 --> NaHSO4 + HCl
30
Give the products, equations and observations for when concentrated sulfuric acid is added to NaBr
NaBr + H2SO4 --> NaHSO4 + HBr The HBr then goes on to react with the sulfuric acid: 2HBr + H2SO4 --> 2H2O + SO2 + Br2 HBr - misty fumes Br2 - brown fumes SO2 - Colourless gas with a choking smell
31
What are the two half equations for the reaction of NaBr and H2SO4?
2Br- --> Br2 + 2e- H2SO4 + 2H+ + 2e- --> 2H2O + SO2
32
Give the products, equations and observations for the reaction of NaI and H2SO4
NaI + H2SO4 --> NaHSO4 + HI Hydrogen iodide goes on to react with H2SO4: 6HI + H2SO4 --> 4H2O + S + 3I2 Sulfuric acid is reduced to hydrogen sulfide: H2SO4 + 8e- + 8H+ --> H2S + 4H2O Observations: HI - misty fumes I2 - purple fumes or black solid SO2 - colourless gas with choking smell S - yellow solid H2S - colourless gas with rotten egg smell
33
What is the trend in temperature of the hydrogen halides?
HF > HCl > HBr > HI
34
How does reducing ability of the hydrogen halides change as you go down the group?
Increases -due to bond strength decreasing
35
Uses of chlorine
- Water purifier - bleach - solvents - CFC's
36
Equation of HBr reacting with water
HBr + H2O --> H3O+ + Br- Forms hydrobromic acid and bromide ions
37
Give the equation for the reaction between hydrogen chloride and water
HCl + H20 --> H3O+ + Cl- Forms hydrochloric acid
38
Give the equation for the reaction between HI and H2O
HI + H20 --> H3O+ + I-
39
Products of hydrogen halides reacting with ammonia. Give an example
Form salts which are white ionic solids
40
Give the equation for the reaction between hydrogen chloride gas and ammonia gas
NH3(g) + HCl(g) --> NH4Cl(s)
41
What is special about fluoride ions when you add silver nitrate to them?
They don't form a silver halide precipitate

CHEMISTRY (18 decks)

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