Group 7 Flashcards

1
Q

Why does the boiling point of Group 7 elements increase down the group?

A

” increased number of electrons in larger atoms, the van der waals forces between molecules increase so more energy is required to separate the molecules

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2
Q

Why does the atomic radius of the Group 7 elements increase down the group?

A

“the greater the atomic number the more electrons there are, these go into shells increasingly further from the nucleus

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3
Q

Why does the electronegativity of the Group 7 elements decrease down the group?

A

“There is an increasing number of shells so more shielding and less pull on the outer electrons and an increasing atomic radius so attraction of nucleus for outer electrons drops off as distance increases

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4
Q

What is the trend in oxidising power of Group 7 elements down the group?

A

It decreases

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5
Q

Why does the oxidising power of Group 7 elements decrease down the group?

A

“the increasing nuclear charge which should attract electrons more is offset by INCREASED SHIELDING and INCREASING ATOMIC RADIUS

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6
Q

Write a balanced chemical equation with state symbols for the reaction of Chlorine with Sodium Bromide

A

“Cl2(aq) + 2NaBr(aq) ——> Br2(aq) + 2NaCl(aq)

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7
Q

Write an balanced ionic equation for the reaction of Bromine with Iodide ions.

A

“Br2 + 2I¯ ——> I2 + 2Br¯

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8
Q

What observation would be made with bromine is reacted with sodium chloride?

A

“Solution goes from colourless to orange-red

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9
Q

What observation would be made with chlorine is reacted with sodium iodide?

A

No visible reaction.

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10
Q

What observation would be made when solid sodium chloride reacts with concentrated sulfuric acid.

A

Steamy Fumes

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11
Q

What a balanced equation for when solid sodium chloride reacts with concentrated sulfuric acid.

A

“NaCl + H2SO4 → NaHSO4 + HCl

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12
Q

Write down three observations that would be made when sodium bromide reacts with concentrated sulfuric acid.

A

steamy fumes, brown fumes, a colourless gas

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13
Q

Name the three gases produced that would be made when sodium bromide reacts with concentrated sulfuric acid.

A

Hydrogen Bromide, Bromine and Sulfur Dioxide.

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14
Q

Write two ionic equations that show the formation of the three gases formed when sodium bromide reacts with concentrated sulfuric acid.

A

H+ + Br- → HBr and H2SO4 + 2 H+ + 2 Br- → Br2 + SO2 + 2 H2O

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15
Q

Write down five observations that would be made when sodium iodide reacts with concentrated sulfuric acid.

A

White fumes, Orange fumes, Colourless gas, Yellow solid, Bad Egg Smell

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16
Q

Name the three gases produced when sodium Iodide reacts with concentrated sulfuric acid.

A

“Hydrogen Iodide, Iodine, Sulfur Dioxide, Sulfur, Hydrogen Sulfide

17
Q

Write an ionic equation that shows the formation of Iodine and Sulfur Dioxide when sodium iodide reacts with concentrated sulfuric acid.

A

H+ + I- → HI

18
Q

Write an ionic equation that shows the formation of iodine and sulfur dioxide when sodium iodide reacts with concentrated sulfuric acid.

A

H2SO4 + 2 H+ + 2 I- → I2 + SO2 + 2 H2O

19
Q

Write an ionic equation that shows the formation of iodine and sulfur when sodium iodide reacts with concentrated sulfuric acid.

A

H2SO4 + 6 H+ + 6 I- → 3 I2 + S + 4 H2O

20
Q

Write an ionic equation that shows the formation of iodine and Hydrogen Sulfide when sodium iodide reacts with concentrated sulfuric acid.

A

H2SO4 + 8 H+ + 8 I- → 4 I2 + H2S + 4 H2O

21
Q

Explain why the ability of halide ions to acts as reducing agents increases down the group.

A

“Down the group it becomes easier to lose an electron because ions are larger & there is more shielding (due to extra electron shell)

22
Q

List the four steps for testing an unknown solution for halide ions

A

“acidify with dilute nitric acid, add a few drops of silver nitrate solution, treat any precipitate with dilute ammonia solution, if a precipitate still exists, add concentrated ammonia solution

23
Q

What is observation for a positive result to show the presence of chloride ions?

A

white ppt soluble in dilute ammonia

24
Q

What is observation for a positive result to show the presence of bromide ions?

A

“cream ppt insoluble in dilute ammonia but soluble in conc.

25
Q

What is observation for a positive result to show the presence of iodide ions?

A

“yellow ppt insoluble in dilute and conc. ammonia solution

26
Q

Write an ionic equation with state symbols for the formation of silver fluoride

A

“Ag+(aq) + F¯(aq) ——> AgF (s)

27
Q

Write an equation with state symbols for the reactions of chlorine with water

A

Cl2(g) + H2O(l) HCl(aq) + HOCl(aq)

28
Q

Why is the reaction of chlorine with water called a DISPROPORTIONATION reaction?

A

Because chlorine is simultaneously oxidised and reduced.

29
Q

What is the chemical test for chlorine?

A

“Blue litmus will be turned red then decolourised in chlorine water

30
Q

Write a balanced chemical equation with state symbols for the reaction of Chlorine with cold aqueous sodium hydroxide

A

2NaOH(aq) + Cl2(g) —> NaCl(aq) + NaOCl(aq) + H2O(l)

31
Q

Explain in terms of the changes in oxidation number why the reaction of Chlorine and cold aqueous sodium hydoride is an example of a DISPROPORTIONATION reaction.

A

Chlorine changes from 0 to -1 and 0 to +1 in the same reaction.