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A LEVEL CHEM > 2.4 Periodicity of Period 3 > Flashcards

2.4 Periodicity of Period 3 Flashcards

1
Q

give the equation and observations when sodium reacts with cold water

A

2Na(s) + 2H2O(l) > 2NaOH(aq) +H2(g)

fizzes around on surface

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2
Q

give the equations for magnesium reacting with steam and water

A

steam : Mg(s) + H2O(g) > MgO(s) +H2(g)

water : Mg(s) + 2H2O(l) > Mg(OH)2 + H2(g)

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3
Q

what are the trends in the reactions of elements with oxygen

A
  • all react with oxygen to form oxides
  • sodium burns with a yellow foame to produce a white solid
  • Mg, Al, Si and P burn with a white flame to give white solid smoke.
  • S burns with a blue flame to form an acidic choking gas
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4
Q

give the equations for the elements with oxygen

A

2Na + 2O2 > 4Na2O
2Mg + O2 > 2MgO
4Al + 3O2 > 2Al2O3
Si + O2 > SiO2
4P + 5O2 > P4O10
S + O2 > SO2

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5
Q

why is sodium stored under oil and phosphorus under water?

A

to stop these elements coming into contact and reacting with air

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6
Q

what are the ionic oxides?

A

Na2O, MgO, Al2O3

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7
Q

what is the macromolecular oxide?

A

SiO2

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8
Q

what are the simple molecular oxides?

A

P4O10 and SO2

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9
Q

why do the ionic oxides have high melting points?

A
  • they have giant ionic lattice structures
  • strong forces of attraction between oppositely charged ions, so higher mp
  • ionic because of large electronegativity difference between metal and O
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10
Q

why does SiO2 have a high melting point and boiling point?

A
  • macromolecular
  • contains many very strong covalent bonds between atoms
  • high energy needed to break them
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11
Q

why do the simple molecular oxides have lower mps and bps?

A
  • weak intermolecular forces betwen molcules
  • vdw and dipole dipole
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12
Q

why does P4010 have a higher mp than SO2?

A
  • it is a bigger molecule so it has more electrons so larger van der waal forced between molecules
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13
Q

why do the melting points increase of the oxides from Na to Al

A
  • increased charge on cation makes the ionic forces stronger, so increasing melting points
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14
Q

why does Al2O3 show covalent character?

A
  • electronegativity difference being less big or alternatively by the small ion aluminium ion with a high charge being able to get close to the oxide ion distorting the charge cloud
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15
Q

how can we prove compounds contain ions?

A
  • melt the solids and show they conduct electricity
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16
Q

why is aluminium oxide insoluble in water?

A
  • high lattice strength makes this layer impermeable to water and air
17
Q

why are the ionic oxides basic?

A
  • the oxide ions accept protons to become hydroxide ions
18
Q

give the equation for sodium oxide reacting with water and the pH

A

Na2O + H2O > 2Na+ + 2OH-

ph 13

19
Q

give the equation for magnesium oxide reacting with water and the pH

A

MgO + H20 > Mg(OH)2

pH 9

20
Q

why is Mg(OH)2 only slightly soluble in water?

A

its lattice is stronger, so fewer free OH- ions are produced so lower pH

21
Q

why do Al2O3 and SiO2 not dissolve in water

A

high strength of the Al2O3 ionic lattice and macromolecular SiO2 structure

pH 7

22
Q

why is MgO better than NaOH for treating acid in rivers and the stomach?

A
  • MgO is sparingly soluble and weakly alkaline so using an excess would not make the water excessively alkaline
23
Q

give the reaction between phosphorus pentoxide and water and the pH

A

P4O10 + 6H20 > 4H3PO4

pH 0

24
Q

give the reaction and ionic equation between sulfur dioxide and water
and pH

A

SO2 + H20 > H2SO3

SO2 + H2O > HSO3- + H+

pH 3 ( weak acid )

25
Q

give the reaction, ionic equation and pH between sulfur trioxide and water

A

SO3 + H2O > H2SO4

SO3 + H2O > HSO4- + H+

pH 0

26
Q

what is the pattern for acid + base reactions

A

acid + base > salt + water

27
Q

give the reactions between sodium oxide and HCl and H2SO4

A

Na2O + 2HCl > 2NaCl + H2O

Na2O + H2SO4 > Na2SO4 + H2O

Na2O + 2H+ > 2Na+ + H2O

28
Q

give the equations for magnesium oxide reacting with

29
Q

what is meant by amphoteric?

A
  • able to act as as an acid and a base
30
Q

give the reaction between aluminium oxide and HCl and H2SO4 and the ionic equation

A

Al2O3 + 6HCl > 2AlCl3 + 3H2O

Al2O3 + 3H2SO4 > Al2(SO4)3 + 3H2O

Al2O3 + 6H+ > 2Al3+ + 3H2O

31
Q

give the reactions for aluminium oxide acting as an acid

A

Al2O3 + 2NaOH + 3H2O > 2NaAl(OH)4

Al2O3 + 2OH- + 3H2O > 2Al(OH)4-

32
Q

give the reactions between phosophoric pentoxide and Na2O and NaOH

A

P4O10 + 12NaOH > 4Na3PO4 + 6H2O

P4O10 + 6Na2O > 4Na3PO4

P4O10 + 12OH- > 4PO43- + 6H2O

33
Q

give the reactions for NaOH reacting with SO2 and SO3

A

SO2 + 2NaOH > Na2SO3 + H2O

SO3 + 2NaOH > Na2SO4 + H2O

X + 2OH- > X2- + H2O

34
Q

why cant SiO2 dissolve or react with water and weak solution of alkali?

A
  • giant covalent structure with very strong bonds

A LEVEL CHEM (22 decks)

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