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Chemistry A2 > Properties of Period 3 elements/oxides > Flashcards

Properties of Period 3 elements/oxides Flashcards

1
Q

State which period 3 elements react with water

A
  • sodium
  • magnesium
  • chlorine
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2
Q

Describe reaction between sodium and water

A

2Na + 2H20 -> 2NaOH + H2

  • metal skates on surface of water
  • exothermic so sodium might ignite (burn orange flame)
  • effervescence (hydrogen gas)
  • forms strong alkaline solution
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3
Q

Describe reaction between magnesium and water at room temperature

A

Mg + 2H2O (l) -> Mg(OH)2 + H2

  • slow reaction
  • few bubbles (hydrogen gas) on surface of magnesium
  • forms less alkaline solution since Mg(OH)2 is sparingly soluble
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4
Q

Describe reaction between magnesium and steam

A

Mg + H2O (g) -> MgO + H2

  • white solid magnesium oxide
  • hydrogen gas
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5
Q

Describe reaction between sodium and oxygen

A
  • burns yellow flame

- white solid Na2O formed

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6
Q

Describe reaction between magnesium and oxygen

A
  • burns bright white flame

- white solid MgO formed

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7
Q

Describe reaction between aluminium and oxygen

A
  • burns bright white flame

- white solid Al2O3 formed

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8
Q

Describe reaction between silicon and oxygen

A
  • white solid SiO2 formed (if heated strongly enough)
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9
Q

Describe reaction between (white) phosphorus and oxygen

A

P4 + 5O2 -> P4O10

  • ignites spontaneously in air
  • burns with white flame
  • cloud of white smoke P4O10
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10
Q

Describe reaction between sulfur and oxygen

A

S + O2 -> SO2
(2SO2 + O2 -> 2SO3)
- burns with blue flame
- pungent SO2 fumes

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11
Q

State structure and bonding in highest oxides of elements Na-S

A

Na2O - giant ionic lattice/ionic
MgO - giant ionic/ionic
Al2O3 - giant ionic with covalent character
SiO2 - giant covalent (macromolecule)/covalent
SO3 - molecular covalent

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12
Q

Explain trend in melting points of highest oxides of the elements Na–S

A
  • increases to highest (MgO) then decreases
  • increase in charge density of Na+ compared to Mg2+ ion means stronger ionic bonding
  • Al3+ has high charge density so distorts O2- so oxide has covalent character (irregular compared to lattice)
  • many covalent bonds in SiO2
  • P4O10 is larger molecule compared to SO3 so has stronger van der Waals
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13
Q

Describe reaction between Na2O and water

A

Na2O + H2O -> 2NaOH

  • strong alkaline solution formed (pH around 14)
  • exothermic
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14
Q

Describe reaction between MgO and water

A

MgO + H2O -> Mg(OH)2

- weak alkaline solution (pH around 9)

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15
Q

Describe reaction between Al2O3 and water

A

insoluble so no reaction (pH 7)

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16
Q

Describe reaction between SiO2 and water

A

insoluble so no reaction (pH 7)

17
Q

Describe reaction between P4O10 and water

A

P4O10 + 6H2O -> 4H3PO4

- acidic solution formed (pH 1-2) NOT A WEAK ACID

18
Q

Describe reaction between SO2 and water

A

SO2 + H2O -> H2SO3 (sulfurous acid)

- acidic solution formed (pH 2-3)

19
Q

Describe reaction between SO3 and water

A

SO3 + H2O -> H2SO4 (sulfuric acid)

- acidic solution formed (0-1)

20
Q

Give equation for reaction between Na2O and acid/alkali

A

acid - Na2O + 2H+ -> 2Na+ + H2O
alkali - none
nature of oxide = basic

21
Q

Give equation for reaction between MgO and acid/alkali

A

acid - MgO + 2H+ -> Mg2+ + H2O
alkali - none
nature of oxide = basic

22
Q

Give equation for reaction between Al2O3 and acid/alkali

A

acid - Al2O3 + 6H+ -> 2Al3+ + 3H2O
alkali - Al2O3 + 3H2O + 2OH- -> 2[Al(OH)4]-
nature of oxide = amphoteric

23
Q

Give equation for reaction between P4O10 and acid/alkali

A

acid - none
alkali - P4O10 + 12OH- ->4PO43- + 6H2O
nature of oxide = acidic

(know P4O10 > PO43- then write out ionic equation and then replace H+ with OH-)

24
Q

Give equation for reaction between SO2 and acid/alkali

A

acid - none
alkali - SO2 +2OH- -> SO32- H2O
nature of oxide = acidic

25
Q

Give equation for reaction between SO3 and acid/alkali

A

acid - none
alkali - SO3 +2OH- -> SO42- H2O
nature of oxide = acidic

26
Q

Suggest why period 3 metallic elements form basic oxides hence alkaline solutions in water

A
  • metal oxides have ionic bonding so contain O2-

- O2- can accept H+ from water to form OH-

27
Q

Suggest why Al2O3 and SiO2 do not react with water

A
  • Al2O3 strong bonding due to covalent character

- SiO2 has giant covalent structure which is insoluble

28
Q

Outline an experiment that could be used to show that aluminium oxide contains ions

A
  • heat until molten (do not dissolve in water since insoluble)
  • electrolyse and identify Al and O2 at electrodes
29
Q

Explain the trend in reactions of Period 3 oxides with water and why MgO forms weaker solution than Na2O

A
  • Na2O and MgO are basic so form hydroxides since they contain oxide ion which has a tendency to combine with H+
  • Mg(OH)2 less soluble than NaOH so forms weaker alkaline solution
  • Al2O3 does not react with water since oxide ion held too strongly in lattice
  • SiO2 does not react with water since giant covalent structure is insoluble
  • P4O10 and SO3 are acidic so form acids with water since they accept lone pair of electrons from oxygen on water
30
Q

Give equation for reaction between SiO2 and acid/alkali

A

acid - none
base - SiO2 + 2OH- -> SiO32- + H2O
nature of oxide = weak acidic

31
Q

Write equation for reaction between Na2O then MgO with P4O10 and state type of reaction

A

6Na2O + P4O10 -> 4Na3PO4
6MgO + P4O10 -> 2Mg3(PO4)2
acid-base reaction
(no need to write out half equations to show them behaving as acidic / basic - just know Na2O > Na+ and MgO > Mg2+ while P4O10 > PO43-)

32
Q

State physical properties of SiO2

A
  • insoluble
  • non conductor
    (high melting/boiling point might not score mark)
33
Q

Write ionic equation and overall equation for reaction between Al2O3 and HCl then NaOH

A

ionic
Al2O3 + 6H+ -> 2Al3+ + 3H2O
Al2O3 + 3H2O + 2OH- -> 2[Al(OH)4]-
(reject HCl or NaOH; only allow Cl- or Na+ as spectator ions)

overall
Al2O3 + 6HCl -> 2AlCl3 + 3H2O
Al2O3 + 3H2O + 2NaOH -> 2Na[Al(OH)4]

34
Q

Describe how to prove SiO2 is acidic

A
  • react with NaOH

- neutralises base (pH7)

35
Q

Explain why SiO2 is insoluble in water

A
  • macromolecular
  • many strong covalent bonds
  • water cannot supply sufficient energy to break bonds
36
Q

Problems with acid rain caused by SO2 and why removed SO2

A
  • toxic breathing problems
  • erodes buildings
  • reduce waste
  • produce H2SO4

Chemistry A2 (12 decks)

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