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a-level oxford chem > 3.2.4 Properties of Period 3 Elements and their Oxides and Chlorides > Flashcards

3.2.4 Properties of Period 3 Elements and their Oxides and Chlorides Flashcards

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1
Q

Explain why sodium is more reactive than magnesium

A
  • ∵ it takes less energy to lose 1 electron than to lose 2
  • ∴ more energy (usually heat) is needed for magnesium to react
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2
Q

Sodium is more reactive than magnesium and this is shown in their reactions with ___

A

water

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3
Q

Describe how sodium reacts with cold water

A
  • Reacts vigorously
  • Forms molten ball on surface
  • Fizzing
    • Produces H2 gas
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4
Q

Write the equation for when sodium reacts with water

A
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5
Q

Describe how magnesium react with cold water

A
  • Reacts very slowly
  • Forms weakly alkaline solution
  • Forms thin coating of magnesium hydroxide forms on surface of the metal
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6
Q

Why is the solution produced from when magnesium reacts with cold water weakly alkaline?

A
  • ∵ magnesium hydroxide is not very soluble in water as its lattice is stronger
    • it’s sparingly soluble
  • ∴ few hydroxide ions are produced
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7
Q

State the equation for when magnesium reacts with cold water

A
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8
Q

Describe how magnesium reacts with steam

A
  • Magnesium reacts faster with steam (i.e. when there’s more energy)
  • To form magnesium oxide
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9
Q

State the equation for when magnesium reacts with steam

A
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10
Q

When Period 3 elements react with oxygen, what do they form?

A

oxides

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11
Q

When Period 3 elements react with oxygen, they are usually oxidised to their _____ oxidation states, same as their _____ _____

A

When Period 3 elements react with oxygen, they are usually oxidised to their highest oxidation states, same as their group numbers

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12
Q

Reactions with Oxygen

State which Period 3 element isn’t oxidised to their highest oxidation state & state its oxidation state

A
  • Sulfur forms SO₂
  • +4 oxidation state
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13
Q

Reactions with Oxygen

Explain why sulfur isn’t oxidised to its highest oxidation state

A

A high temp. and catalyst is needed to make SO3, where S has oxidation state of +6

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14
Q

More ____ metals (Na, Mg) and _____ (P, S) react readily in air, while ___ and ___ react slowly

A

More reactive metals (Na, Mg) and non-metals (P, S) react readily in air, while Al and Si react slowly

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15
Q
A
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16
Q
A
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17
Q

Na2O, MgO & Al2O3 have ____ melting points

A

high

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18
Q

Explain why Na2O, MgO & Al2O3 have high melting points

A
  • Giant ionic lattices
  • Strong forces of attraction between ions = lots of energy needed to break bonds
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19
Q

MgO has a ____ melting point than Na2O

A

higher

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20
Q

Why does MgO have a higher melting point than Na2O?

A
  • Mg forms 2+ ions
  • So bonds more strongly than 1+ Na ions in Na2O
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21
Q

Al2O3 has a ____ melting point than MgO

A

lower

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22
Q

Why does Al2O3 have a lower melting point than MgO?

A
  • ∵ of difference in electronegativity between Al and O isn’t as large as between Mg and O
  • Means oxygen ions in Al2O3 don’t attract electrons in metal-oxygen bond as strongly MgO
  • Makes bonds in Al2O3 partially covalent
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23
Q

SiO2 has a _____ melting point than non-metal oxides

A

higher

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24
Q

Why does SiO2 have a higher melting point than non-metal oxides

A
  • ∵ has giant macromolecular structure
  • Have to break strong covalent bonds = lots of energy
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25
Q

Why does P4O10 and SO2 have low melting points?

A
  • ∵ form simple molecular structure
  • Have weak intermolecular forces (dipole-dipole and van der Waals)
  • Take little energy to break
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26
Q

State the equation for when sodium and oxygen react, include state symbols

A
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27
Q

State the equation for when aluminium and oxygen react, include state symbols

A
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28
Q

State the equation for when phosphorus and oxygen react, include state symbols.

A
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29
Q

State the equation for when magnesium and oxygen react, include state symbols

A
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30
Q

State the equation for when silicon and oxygen react, include state symbols

A
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31
Q

State the equation for when sulfur and oxygen react, include state symbols

A
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32
Q

Ionic Oxides are _____

A

Alkaline

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33
Q

Covalent Oxides are ____

A

Acidic

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34
Q

Explain why ionic oxides are alkaline

A
  • Ionic oxides (of Na and Mg) contain oxide ions (O2-)
  • When they dissolve in water, O2- ions accept protons from water molecules to form hydroxide ions
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35
Q

Explain why the ionic oxides of Na are more alkaline than those for Mg

A

Sodium hydroxide is more soluble in water ∴ more alkaline solution than magnesium hydroxide

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36
Q

State the equation for when sodium oxide reacts with water and include rough pH of solution formed

A
37
Q

State the equation for when magnesium oxide reacts with water and include rough pH of solution formed

A
38
Q

Explain why covalent oxides (e.g. oxides of phosphorus and sulfur) are acidic

A

They dissociate in solution forming hydrogen ions and negative ion (called conjugate base)

39
Q

Simple covalent oxides of non-metals phosphorus and sulfur form acidic solutions that are ___ so the pH is around ___

A

Simple covalent oxides of non-metals phosphorus and sulfur form acidic solutions that are strong so the pH is around 0-2 (for at least 1 mol dm-3)

40
Q

State the equation for when phosphorus(V) oxide reacts with water. Include pH.

A

pH = 0

41
Q

State the equation for when sulfur dioxide reacts with water. Include pH.

A

pH = 3

42
Q

State the equation for when sulfur trioxide reacts with water. Include pH.

A

pH = 0

43
Q

State the equation for the dissociation of phosphoric(V) acid

A
44
Q

State the equation for the dissociation of sulfurous acid (or sulfuric(IV) acid)

A
45
Q

State the equation for the dissociation of sulfuric(VI) acid

A
46
Q

State which Period 3 oxides are insoluble in water

A
  • Aluminium oxide
  • Silicon dioxide
47
Q

Silicon dioxide is ______ because it…

A

Silicon dioxide is acidic because it reacts with bases to form salts

48
Q

Explain why Al2O3 and SiO2 do not dissolve in water

A
  • ∵ of the high strength of the Al2O3 ionic lattice and the SiO2 macromolecular structure/giant covalent structure
  • Give a neutral pH 7
49
Q

Aluminium oxide is ______ because it….

A

amphoteric ∵ reacts with acids and bases to form salts

50
Q

Basic oxides netutralise _____

A

acids

51
Q

Basic oxides netutralise acids:

Na2O(s) + 2HCl(aq) → ….

A

Na2O(s) + 2HCl(aq) → 2NaCl(aq) + H2O(I)

52
Q

Basic oxides netutralise acids:

MgO(s) + H2SO4(aq) → ….

A

MgO(s) + H2SO4(aq) → MgSO4(aq) + H2O(l)

53
Q

Acidic oxides neutralise bases:

A
54
Q

Acidic oxides neutralise bases:

A
55
Q

Acidic oxides neutralise bases:

A
56
Q

Acidic oxides neutralise bases:

A
57
Q

Amphoteric oxides neutralise acids and bases:

A
58
Q

Amphoteric oxides neutralise acids and bases:

A
59
Q

State what you would observe when sodium reacts with oxygen

(excluding its speed e.g. vigorous)

A

Sodium burns with a yellow flame to produce a white solid

60
Q

State what you would observe when Mg, Al, Si and P reacts with oxygen

(excluding its speed)

A

Mg, Al, Si and P burn with a white flame to give white powder (Mg & Al) / smoke

61
Q

State what you would observe when sulfur reacts with oxygen

(excluding its speed)

A

S burns with a blue flame to form an acidic choking gas

62
Q

Explain why aluminium metal appears unreactive

A
  • Has thin layer of aluminium oxide
  • The high lattice strength of aluminium oxide and its insolubility in water make this layer impermeable to air and water
63
Q

All elements from Na to S, react directly with chlorine if _____ to form chlorides

A

heated

64
Q
A
65
Q
A
66
Q
A
67
Q

From Na to S, why does the bonding change from ionic to covalent?

A

Bonding is due to decrease in electronegativity from Na to S

68
Q

Describe how sodium chloride and magnesium chloride reacts with water

A
  • Sodium chloride and magnesium chloride dissolve in water to form neutral solutions
  • Containing ions Na+, Cl- and Mg2+
    • which are hydrated (aq)
69
Q

Describe how aluminium chloride reacts with water

A
  • Aluminium chloride reacts rapidly and vigorously with water to give an acidic solution (colourless solution in excess water)
  • Contains H+ and Cl-
  • Some hydrated Al3+ ions are formed
70
Q

Why is the solution produced from aluminium chloride reacting with water acidic?

A

Al3+ ion pull electrons towards it from Al—O bonds = loss of H+ ion = acidic solution

71
Q

State the equation for when aluminium chloride reacts with (a little bit of) water

A

AlCl3(s) + 3H2O(l) → Al(OH)3(s) + 3H+(aq) + 3Cl-(aq)

72
Q

Describe how silicon tetrachloride reacts with water

A

It reacts violently with cold water to form a strongly acidic solution & colourless ‘silica’ gel

73
Q

State the equation for when silicon tetrachloride reacts with water

A

SiCl4(l) + 2H2O(l) → SiO2(s) + 4H+(aq) + 4Cl-(aq)

74
Q

Describe what happens when phosphorus pentachloride reacts with water

A

It reacts with boiling water to produce phosphoric acid and hydrochloric acid

75
Q

State the equation for when phosphorus pentachloride reacts with water

A

PCl5(s) + 4H2O(l) → H3PO4(aq) + 5H+(aq) + 5Cl-(aq)

76
Q

Suggest why the melting point of magnesium oxide is much higher than the melting point of magnesium chloride (2)

A
  • Charge on oxide ion bigger than on chloride
  • Therefore electrostatic attraction is stronger
77
Q

Na2O + H2O & P4O10 + H2O are _____ _______ reactions

A

Na2O + H2O & P4O10 + H2O are vigorous exothermic reactions

78
Q

Aluminium oxide is partially _____ and partially ______ bonded

A

Aluminium oxide is partially ionic and partially covalently bonded

79
Q

Aluminum chlorides are ______ with ________

A

Aluminum chlorides are largely ionic with lots of covalent character

80
Q

AlCl3 and Al2Cl6 form in the ___ phase

A

gas

81
Q

Describe the bonding in AlCl3

A

Has 6 outer electrons & forms a dimer - co-ordinate covalent bonds form between lone pairs of electrons in chlorine atoms and (electron-deficient) aluminium atoms

82
Q

Draw Al2Cl<span>6</span>

A
83
Q

Draw [Al(H2O)6]3+

A
84
Q

State the equation for when aluminium chloride reacts with excess water and state the pH of the solution (2)

A

AlCl3 + 6H2O → [Al(H2O)6]3+ + 3Cl-

Below 6.9

85
Q

Write an ionic equation to show how aluminium oxide reacts with aqueous sodium hydroxide (1)

A

Al2O3 + 2OH– +3H2O → 2Al(OH)4–

86
Q

State why NaCl forms a neutral solution

A

no reaction or no hydrolysis or only dissolving occurs

87
Q

Suggest why sulfur dioxide forms a weakly acidic solution (1)

A

Reaction is an equilibrium / reversible reaction displaced mainly to the left / partially ionised / dissociated

88
Q

Write an ionic equation for the reaction of phosphorus(V) oxide with an excess of sodium hydroxide solution (1)

A

P4O10 + 12OH– → 4PO43- + 6H2O

a-level oxford chem (34 decks)

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