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Chemistry A Level > A2 - Periodicity > Flashcards

A2 - Periodicity Flashcards

1
Q

What is Periodicity?

A

The repeating patterns / trends of physical or chemical properties or reactions.

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2
Q

Reaction of Sodium with cold water What pH?

A
  • vigorous reaction - floats on surface pH of 12-14
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3
Q

Equation for reaction of Sodium with cold water

A

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

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4
Q

Reaction and equation of Magnesium with Cold water. Give pH value

A
  • very slow - partially soluble pH of 9/10 Mg (s) + 2H2O (l) —> Mg(OH)2 (aq) + H2 (g)
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5
Q

Reaction and equation of Magnesium with Hot water (steam). Give observation.

A
  • faster reaction - white solid formed Mg (s) + H2O (g) —> MgO (s) + H2 (g)
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6
Q

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

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

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

A

Oxides

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8
Q

Are group 1 ions more acidic or alkali?

A

More alkali because they are very soluble in aqueous solution so release more OH- ions so are more alkali

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9
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
  • Which has a +4 oxidation state
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10
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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11
Q

Reactions with Oxygen

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

A

A high temperature and catalyst is needed to make SO3, where sulfur has an oxidation state of +6

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12
Q

Reactions with oxygen

Sodium and oxygen

A

4Na (s) + O2 (g) —-> 2Na2O (s)

White solid of Na2O

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13
Q

Reactions with oxygen

Magnesium and oxygen

A

2Mg (s) + O2 (g) —-> 2MgO (s)

White solid of MgO

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14
Q

Reactions with oxygen

Aluminium and oxygen

A

2Al (s) + 1.5O2 (g) —> Al2O3 (s)

White solid of Al2O3

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15
Q

Reactions with oxygen

Silicon and oxygen

A

Si + O2 (g) —> SiO2 (s)

Sand

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16
Q

Reactions with oxygen

Phosphorus and oxygen

A

P4 (s) + 5O2 (g) —> P4O10 (g)

White solid of P4O10

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17
Q

Reactions with oxygen

Sulfur and oxygen

A

S (s) + O2 (g) —> SO2 (g)

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18
Q

Reactions with oxygen

Sulfur dioxide and oxygen

A

SO2 (g) + 1/2O2 (g) —> SO3 (g)

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19
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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20
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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21
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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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

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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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

Graph of melting points of period 3 oxides

A
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26
Q

What do ionic compounds exert?

A
  • Non-directional electrostatic attraction forces
  • Size of ion decreases across period so can pack more O2- ions around aluminium ion than sodium ion as it is non-directional
27
Q

Ionic oxides are

A

Alkaline

28
Q

Covalent oxides are

A

Acidic

29
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)

30
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
31
Q

What are the 2 assumptions the perfect ionic model is based on:

A
  1. Bonding in compounds is 100% ionic
  2. Ions are regarded as point charges or perfect spheres and are not distorted
32
Q

100% Non polar covalent drawing

Polar covalent drawing

100% ionic

A
33
Q

Ionic with covalent character drawing

A
34
Q

Describe the meanings of values in tables in relation to the perfect ionic model

A
  • If there is no/ little value differences then it is ionic
  • If there is a difference and the larger the difference means the greater the covalent character
35
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)

36
Q

Reactions of oxides with water

Sodium oxide and water and give the pH of the product

A

Na2O (s) + H2O (l) —> 2NaOH (aq)

pH 13/14

37
Q

Reactions of oxides with water

Magnesium oxide and water and give the pH of the product

A

MgO (s) + H2O (l) —> Mg(OH)2 (aq)

pH 10/12

38
Q

Reactions of oxides with water

Aluminium oxide and water

A

No reaction

39
Q

Reactions of oxides with water

Silicon dioxide and water

A

No reaction

40
Q

Reactions of oxides with water

Phosphorus oxide and water and give pH of the product

A

P4O10 (s) + 6H2O (l) —> 4H3PO4 (aq)

pH 0/1

41
Q

Reactions of oxides and water

Sulfur dioxide and water and give the pH of the product

A

SO2 (g) + H2O (l) —> H2SO3

pH 3

42
Q

Reactions of oxides with water

Sulfur trioxide and water and give the pH of the product

A

SO3 + H2O —> H2SO4

pH -1/+1

43
Q

Phosphoric acid drawing

A

Can draw the H next to O

44
Q

Phosphate ion drawing

A
45
Q

What happens in the reactions of acids with bases?

Give the word equation

A

Metal oxides are bases so will react with acids and non-metal oxides

  • Metal oxide + acid —-> salt + water
46
Q

Reactions of acids and bases

Sodium oxide and hydrochloric acid equation

A

Na2O (s) + 2HCl (aq) —> 2NaCl (aq) + H2O (l)

47
Q

Reactions of acids and bases

Magnesium Oxide and nitric acid

A

MgO (s) + 2HNO3 (aq) —> Mg(NO3)2 (aq) + H2O (l)

48
Q

Reactions with acids and bases

Sodium oxide and sulfuric acid

A

Na2O (s) + H2SO4 (aq) —> Na2SO4 (aq) + H2O (l)

49
Q

What symbol would NO3- ions have and why?

A

They are all soluble in water so would have aqueous symbol

50
Q

Non metal oxide reactions

Sodium oxide and phosphorus oxide

A

6Na2O (s) + P4O10 (s) —> 4Na3PO4 (s)

51
Q

Non metal oxide reactions

magnesium oxide and phosphorus oxide

A

6MgO (s) + P4O10 (s) —> 2Mg3(PO4)2 (s)

52
Q

Non metal oxide reactions word equation

A

Non metal basic + non-metal acidic —> salt

(In the absence of water)

53
Q

What are amphoteric oxides

A

They can react with both acids and bases

54
Q

Amphoteric oxides

Aluminuim oxide + hydrochloric acid

A

Al2O3 (s) + 6HCl (aq) —> 2AlCl3 (aq) + 3H2O (l)

55
Q

Amphoteric oxides

aluminium oxide and sulfuric acid

A

Al2O3 (s) + 3H2SO4 (aq) —> Al2(SO4)3 (aq) + 3H2O (l)

56
Q

Ionic equation Aluminium oxide with hydrochloric acid or sulfuric acid

A

Al2O3 (s) + 6H+ (aq) —> 2Al3+ (aq) + 3H2O (l)

57
Q

Amphoteric oxides

Aluminium oxide + sodium hydroxide + water

A

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

58
Q

Non-metal oxides react with bases give the word equation

A

Acidic non-metal oxide + base —> salt + water

59
Q

Non-metal oxides react with bases

Silicon dioxide and sodium hydroxide

A

SiO2 + 2NaOH (aq) —> Na2SiO3 + H2O

60
Q

Non-metal oxides react with bases

Phosphorus oxide and sodium hydroxide

A

P4O10 (s) + 12NaOH (aq) —> 4Na3PO4 + 6H2O

61
Q

Non-metal oxides react with bases

Sulfur dioxide and sodium hydroxide

A

SO2 (g) + 2NaOH (aq) —> Na2SO3 + H2O

62
Q

Non metal oxides react with bases

Sulfur trioxide + sodium hydroxide

A

SO3 + 2NaOH —> Na2SO4 (aq) + H2O

63
Q

What colour does universal indicator go for non-metal oxides?

A

Red e.g. SiO2

64
Q

What colour does universal indicator go for metal oxides?

A

Blue / purple

Chemistry A Level (25 decks)

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