3.2.4 Properties of Period 3 Elements and their Oxides and Chlorides Flashcards
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
2
Q
Sodium is more reactive than magnesium and this is shown in their reactions with ___
A
water
3
Q
Describe how sodium reacts with cold water
A
- Reacts vigorously
- Forms molten ball on surface
- Fizzing
- Produces H2 gas
4
Q
Write the equation for when sodium reacts with water
A
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
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
7
Q
State the equation for when magnesium reacts with cold water
A
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
9
Q
State the equation for when magnesium reacts with steam
A
10
Q
When Period 3 elements react with oxygen, what do they form?
A
oxides
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
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
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
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
15
Q
A
16
Q
A
17
Q
Na2O, MgO & Al2O3 have ____ melting points
A
high
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
19
Q
MgO has a ____ melting point than Na2O
A
higher
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
21
Q
Al2O3 has a ____ melting point than MgO
A
lower
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
23
Q
SiO2 has a _____ melting point than non-metal oxides
A
higher
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
25
Why does P4O10 and SO2 have low melting points?
* ∵ form simple molecular structure
* Have weak intermolecular forces (dipole-dipole and van der Waals)
* Take little energy to break
26
State the equation for when sodium and oxygen react, include state symbols
27
State the equation for when aluminium and oxygen react, include state symbols
28
State the equation for when phosphorus and oxygen react, include state symbols.
29
State the equation for when magnesium and oxygen react, include state symbols
30
State the equation for when silicon and oxygen react, include state symbols
31
State the equation for when sulfur and oxygen react, include state symbols
32
Ionic Oxides are \_\_\_\_\_
Alkaline
33
Covalent Oxides are \_\_\_\_
Acidic
34
Explain why ionic oxides are alkaline
* 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
35
Explain why the ionic oxides of Na are more alkaline than those for Mg
Sodium hydroxide is more soluble in water ∴ more alkaline solution than magnesium hydroxide
36
State the equation for when sodium oxide reacts with water and include rough pH of solution formed
37
State the equation for when magnesium oxide reacts with water and include rough pH of solution formed
38
Explain why covalent oxides (e.g. oxides of phosphorus and sulfur) are acidic
They dissociate in solution forming hydrogen ions and negative ion (called conjugate base)
39
Simple covalent oxides of non-metals phosphorus and sulfur form acidic solutions that are ___ so the pH is around \_\_\_
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
State the equation for when phosphorus(V) oxide reacts with water. Include pH.
pH = 0
41
State the equation for when sulfur dioxide reacts with water. Include pH.
pH = 3
42
State the equation for when sulfur trioxide reacts with water. Include pH.
pH = 0
43
State the equation for the dissociation of phosphoric(V) acid
44
State the equation for the dissociation of sulfurous acid (or sulfuric(IV) acid)
45
State the equation for the dissociation of sulfuric(VI) acid
46
State which Period 3 oxides are insoluble in water
* Aluminium oxide
* Silicon dioxide
47
Silicon dioxide is ______ because it...
Silicon dioxide is _acidic_ because it _reacts with bases to form salts_
48
Explain why Al2O3 and SiO2 do not dissolve in water
* ∵ of the high strength of the Al2O3 ionic lattice and the SiO2 macromolecular structure/giant covalent structure
* Give a neutral pH 7
49
Aluminium oxide is ______ because it....
amphoteric ∵ reacts with acids and bases to form salts
50
Basic oxides netutralise \_\_\_\_\_
acids
51
Basic oxides netutralise acids:
Na2O(s) + 2HCl(aq) → ....
Na2O(s) + 2HCl(aq) → 2NaCl(aq) + H2O(I)
52
Basic oxides netutralise acids:
MgO(s) + H2SO4(aq) → ....
MgO(s) + H2SO4(aq) → MgSO4(aq) + H2O(l)
53
Acidic oxides neutralise bases:
54
Acidic oxides neutralise bases:
55
Acidic oxides neutralise bases:
56
Acidic oxides neutralise bases:
57
Amphoteric oxides neutralise acids and bases:
58
Amphoteric oxides neutralise acids and bases:
59
State what you would observe when sodium reacts with oxygen
(excluding its speed e.g. vigorous)
Sodium burns with a yellow flame to produce a white solid
60
State what you would observe when Mg, Al, Si and P reacts with oxygen
(excluding its speed)
Mg, Al, Si and P burn with a white flame to give white powder (Mg & Al) / smoke
61
State what you would observe when sulfur reacts with oxygen
(excluding its speed)
S burns with a blue flame to form an acidic choking gas
62
Explain why aluminium metal appears unreactive
* 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
All elements from Na to S, react directly with chlorine if _____ to form chlorides
heated
64
65
66
67
From Na to S, why does the bonding change from ionic to covalent?
Bonding is due to decrease in electronegativity from Na to S
68
Describe how sodium chloride and magnesium chloride reacts with water
* Sodium chloride and magnesium chloride dissolve in water to form neutral solutions
* Containing ions Na+, Cl- and Mg2+
* which are hydrated (aq)
69
Describe how aluminium chloride reacts with water
* 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
Why is the solution produced from aluminium chloride reacting with water acidic?
Al3+ ion pull electrons towards it from Al---O bonds = loss of H+ ion = acidic solution
71
State the equation for when aluminium chloride reacts with (a little bit of) water
AlCl3(s) + 3H2O(l) → Al(OH)3(s) + 3H+(aq) + 3Cl-(aq)
72
Describe how silicon tetrachloride reacts with water
It reacts violently with cold water to form a strongly acidic solution & colourless 'silica' gel
73
State the equation for when silicon tetrachloride reacts with water
SiCl4(l) + 2H2O(l) → SiO2(s) + 4H+(aq) + 4Cl-(aq)
74
Describe what happens when phosphorus pentachloride reacts with water
It reacts with boiling water to produce phosphoric acid and hydrochloric acid
75
State the equation for when phosphorus pentachloride reacts with water
PCl5(s) + 4H2O(l) → H3PO4(aq) + 5H+(aq) + 5Cl-(aq)
76
Suggest why the melting point of magnesium oxide is much higher than the melting point of magnesium chloride (2)
* Charge on oxide ion bigger than on chloride
* Therefore electrostatic attraction is stronger
77
Na2O + H2O & P4O10 + H2O are _____ \_\_\_\_\_\_\_ reactions
Na2O + H2O & P4O10 + H2O are _vigorous_ _exothermic_ reactions
78
Aluminium oxide is partially _____ and partially ______ bonded
Aluminium oxide is partially ionic and partially covalently bonded
79
Aluminum chlorides are ______ with \_\_\_\_\_\_\_\_
Aluminum chlorides are _largely ionic_ with _lots of covalent character_
80
AlCl3 and Al2Cl6 form in the ___ phase
gas
81
Describe the bonding in AlCl3
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
Draw Al2Cl6
83
Draw [Al(H2O)6]3+
84
State the equation for when aluminium chloride reacts with excess water and state the pH of the solution (2)
AlCl3 + 6H2O → [Al(H2O)6]3+ + 3Cl-
Below 6.9
85
Write an ionic equation to show how aluminium oxide reacts with aqueous sodium hydroxide (1)
Al2O3 + 2OH– +3H2O → 2Al(OH)4–
86
State why NaCl forms a neutral solution
no reaction or no hydrolysis or only dissolving occurs
87
Suggest why sulfur dioxide forms a weakly acidic solution (1)
Reaction is an equilibrium / reversible reaction displaced mainly to the left / partially ionised / dissociated
88
Write an ionic equation for the reaction of phosphorus(V) oxide with an excess of sodium hydroxide solution (1)
P4O10 + 12OH– → 4PO43- + 6H2O
