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Chemistry > Properties of the Period 3 Elements > Flashcards

Properties of the Period 3 Elements Flashcards

1
Q

What is the equation for the reaction of sodium with cold water?

A

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

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2
Q

Describe the reaction of sodium with cold water

A

A vigorous reaction. The metal fizzes rapidly and melts due to the heat released. A strongly alkaline solution is formed.

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3
Q

What is the equation for the reaction of magnesium with cold water?

A

Mg(s) + 2H2O(l) -> Mg(OH)2(aq) + H2(g)

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4
Q

Describe the reaction of magnesium with cold water

A

This is a very slow reaction at room temperature. Only a few bubbles of gas are produced after a day or two. The resulting solution is only a weak alkali because magnesium hydroxide is only sparingly soluble.

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5
Q

What is the equation for the reaction of magnesium with steam?

A

Mg(s) + H2O(g) -> MgO(s) + H2(g)

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6
Q

Describe the reaction of magnesium with steam

A

This reaction is a lot faster due to the higher temperatures needed to generate the steam.

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7
Q

What is the equation for the reaction of chlorine with water (not in the presence of bright sunlight)?

A

Cl2(g) + H2O(l) <-> HClO(aq) + HCl(aq)

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8
Q

What is HClO(aq)?

A

chloric (I) acid

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9
Q

What is the equation for the reaction of chlorine and water in the presence of bright sunlight?

A

2Cl2(g) + 2H2O(l) -> 4HCl(aq) + O2(g)

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10
Q

What does the pH of the resulting solution from the reaction between chlorine and water depend on?

A

depends on the concentration of solution

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11
Q

What is the equation for the reaction between sodium and oxygen?

A

2Na(s) + 1/2O2(g) -> Na2O(s)

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12
Q

Describe the reaction of sodium with oxygen gas

A

burns brightly in oxygen gas with a characteristic yellow flame to form a white solid

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13
Q

Describe the reaction of magnesium with oxygen gas

A

burns brightly in oxygen gas with a brilliant white flame to form a white solid

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14
Q

What is the equation of the reaction between magnesium and oxygen?

A

2Mg(s) + O2(g) -> 2MgO(s)

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15
Q

What is the equation of the reaction between aluminium and oxygen?

A

4Al(s) + 3O2(g) -> 2Al2O3(s)

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16
Q

Describe the reaction between aluminium and oxygen

A

If aluminium powder is heated and lowered into a jar of oxygen it burns with a bright white flame to produce aluminium oxide. Aluminium also reacts with oxygen from the atmosphere in a much slower version of the reaction. This means most pieces of aluminium are dull and grey, coated with a layer of aluminium oxide.

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17
Q

What is the equation of the reaction between silicon and oxygen?

A

Si(s) + O2(g) -> SiO2(s)

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18
Q

Describes the reaction of silicon with oxygen

A

Silicon forms an oxide when heated strongly in oxygen and it burns slowly

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19
Q

As an element what are the two different forms (allotropes) phosphorus can be found as?

A
  1. Red phosphorus is made of chains of P4 tetrahedrons
  2. White phosphorus is a single P4 tetrahedral molecule
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20
Q

Do both allotropes of phosphorus react the same with oxygen?

A

They both undergo the same reaction with oxygen, however the red allotrope must be heated first, whereas the white allotrope reacts rapidly in air.

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21
Q

What is the equation of the reaction between phosphorus and oxygen?

A

4P(s) + 5O2(g) -> P4O10(s)

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22
Q

Describe the reaction of phosphorus with oxygen

A

burns spontaneously with a white flame and smoke

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23
Q

If there is a limited supply of oxygen, what is the equation of the reaction between phosphorus and oxygen?

A

2P(s) + 1.5O2(g) -> P2O3(s)

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24
Q

Describe the reaction of sulfur with oxygen

A

When sulfur powder is heated and lowered into a gas jar of oxygen it reacts to form sulfur dioxide and a little sulfur trioxide
With a higher temperature and a V2O5 catalyst burns in blue flame

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25
Q

What are the equations for the two reactions that take place between sulfur and oxygen?

A

S(s) + O2(g) -> SO2(g)
SO2(g) + 1/2O2(g) -> SO3(l)

26
Q

What is the equation for the reaction between sodium oxide with water?

A

Na2O(s) + H2O(l) -> 2Na+(aq) + 2OH-(aq)

27
Q

What is the equation for the reaction between magnesium oxide and water?

A

MgO(s) + H2O(l) -> Mg(OH)2(aq)

28
Q

The oxides of Na and Mg are both what and react with water to form what pH solution?

A

they are both alkaline and react with water to form basic solutions but magnesium hydroxide is only sparingly soluble and so is only weakly alkaline

29
Q

What are the two oxides that are insoluble in water?

A

Aluminium oxide and silicon dioxide so they undergo no reaction so the pH when they are added to water is 7

30
Q

What is the reaction between phosphorus (V) oxide and water?

A

produces phosphoric (V) acid which is a strong tri-protic acid and fully dissociates - pH 1-2
P4O10(s) + 6H2O(l) -> 4H3PO4(aq)

31
Q

What is the reaction between sulfur dioxide and water?

A

sulfur dioxide dissolves fairly well in water to produce sulfurus acid - this can also be called sulfuric (IV) acid but it is a slightly weaker acid than sulfuric acid
SO2(g) + H2O(l) -> H2SO3(aq) (pH 2-3)

32
Q

What is the reaction between sulfur trioxide and water?

A

sulfur trioxide reacts violently with water to produce sulfuric (V) acid - this is another strong acid which fully dissociates
SO3(g) + H2O(l) -> H2SO4(aq) (pH 0-1)

33
Q

What is the trend in bonding across period 3?

A

across period 3 the bonding changes from being ionic on the left to covalent on the right

34
Q

Why does MgO have the highest melting point of all the P3 oxides?

A
  • MgO has ionic bonds
  • there are strong electrostatic forces of attraction between oppositely charged ions
  • these require a lot of energy to overcome
35
Q

Why does Al2O3 have more covalent character than MgO?

A
  • the Al3+ ion is smaller than the Mg2+ ion
  • this means the Al3+ ion is more polarising than the Mg2+ ion
  • this distorts the electron cloud around the O2- ion more so that there is more electron density shared between the two ions
36
Q

For the oxides of Phosphorus and Sulfur, why does P4O10 have the highest melting point, followed by SO3 then SO2?

A
  • these all have simple molecular structures
  • they all have van der Waals intermolecular forces between molecules
  • P4O10 is the largest molecule so has the strongest VdW, whereas SO2 is the smallest so has the weakest VdW
37
Q

Why does SiO2 have a high melting point?

A
  • this has a macromolecular/giant covalent structure
  • it has lots of covalent bonds
  • which are very strong
38
Q

How do the acid/base properties of the P3 oxides change going across the period?

A

across the period the oxides change from being basic to neutral to acidic

39
Q

What is the relationship between the bonding and acid/base properties of the period 3 oxides?

A
  • the oxides which are ionically bonded tend to be alkaline
  • the oxides which are covalently bonded tend to be acidic
40
Q

What is the equation for the reaction between sodium oxide (basic) with sulfuric acid?

A

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

41
Q

What is the equation between magnesium oxide (basic) and hydrochloric acid?

A

MgO(s) + 2HCl(aq) -> MgCl2(aq) + H2O(l)

42
Q

What does amphoteric mean? and which P3 oxides are amphoteric?

A

it can act as an acid or a base and aluminium oxide and silicon dioxide

43
Q

What is the equation for the reaction between aluminium oxide and hydrochloric acid?

A

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

44
Q

What is the equation between aluminium oxide and sodium hydroxide and what is a condition required for this reaction?

A

Al2O3(s) + 2NaOH(aq) -> 2NaAl(OH)4(aq) + 3H2O(l) and this reaction requires hot concentrated sodium hydroxide

45
Q

What is the equation for the reaction between silicon dioxide and sodium hydroxide and what is a condition required for this reaction?

A

SiO2(s) + 2NaOH(aq) -> Na2SiO3(aq) + H2O(l) and it requires hot concentrated sodium hydroxide to react as an acid

46
Q

How strong of an acid is hydrofluoric acid?

A

HF is an extremely strong acid

47
Q

What is the equation for the reaction between silicon dioxide and hydrofluoric acid?

A

SiO2(s) + 4HF(aq) -> SiF4(aq) + 2H2O(l)

48
Q

What happens when P4O10 is added to an alkaline solution?

A

first it reacts with the water present to form phosphoric acid which means it is really phosphoric acid which reacts with the base which occurs in stages depending on how much base is present

49
Q

What are the equations for the stages of which phosphoric acid reacts with a base (e.g. NaOH) and what is the overall equation? Also, what is the equation starting from P4O10 as the reactant?

A

H3PO4(aq) + NaOH(aq) -> NaH2PO4(aq) + H2O(l)
NaH2PO4(aq) + NaOH(aq) -> Na2HPO4(aq) + H2O(l)
Na2HPO4(aq) + NaOH(aq) -> Na3PO4(aq) + H2O(l)
Overall: H3PO4(aq) + 3NaOH(aq) -> Na3PO4(aq) + 3H2O(l)
P4O10 + 12NaOH -> 4Na3PO4(aq) + 6H2O(l)

50
Q

What is the equations for the stages of which sulfur dioxide reacts with a basic solution of NaOH and what is the overall equation?

A

SO2(aq) + NaOH(aq) -> NaHSO3(aq)
NaHSO3(aq) + NaOH(aq) -> Na2SO3(aq) + H2O(l)
Overall equation: SO2(aq) + 2NaOH(aq) -> Na2SO3(aq) + H2O(l)

51
Q

What is the equation for the reaction between phosphorus oxide and sodium oxide?

A

P4O10 + 6Na2O -> 4Na3PO4(aq)

52
Q

What is the equation for the reaction between phosphorus oxide and magnesium oxide?

A

P4O10 + 6MgO -> 2Mg3(PO4)2(aq)

53
Q

What is the trend across period 3 for atomic radius and why?

A

atomic radius decreases along the period as there is an increase in nuclear charge and the same amount of shielding which means the electron shells are held closer to the nucleus

54
Q

What is the trend across period 3 for electronegativity?

A

electronegativity increases along the period because there is an increase in nuclear charge and the same amount of shielding which means the elements are increasingly capable of withdrawing electron density from a covalent bond

55
Q

What is the general trend in 1st ionisation energy across period 3?

A

increases along the period as there is an increase in nuclear charge and the same amount of shielding which means the electrons are held increasingly more tightly and so require more energy to be removed

56
Q

What are the two anomalies in the increase in 1st ionisation energy across period 3 and why?

A

Al has a lower 1st IE than Mg because
- Mg has a 3s electron removed
- Al has a 3p electron removed
- 3p is higher in energy than 3s
S has a lower 1st IE than P because
- P has a 3p electron removed which is unpaired
- S has a 3p electron removed which is paired
- S has a lower ionisation energy due to electron pair repulsion

57
Q

Why does the melting point increase from sodium to aluminium?

A
  • the charge on the metal ion increases from Na+ to Al3+
  • the size of the metal ion decreases across the row
  • therefore there is an increase in the strength of attraction between the metal ions and delocalised electrons
58
Q

Which P3 element has the highest melting point?

59
Q

Why does silicon have the highest melting point?

A
  • it has a macromolecular structure
  • with lots of covalent bonds
  • which are very strong
60
Q

What is the pattern in melting point for the non-metals of P3?

A
  • P, S and Cl all have a simple molecular structure with van der Waals intermolecular forces
  • strength of the Van der Waals depends on the size of the molecule and S is the largest (S8), followed by P (P4) then Cl (Cl2)
  • argon exists as single atoms with the weakest Van der Waals out of all of them
61
Q

Which P3 element has the highest BP?

62
Q

Why does aluminium have the highest boiling point?

A
  • Once silicon has been melted most of its strong covalent bonds have been broken, so boiling it requires only a little extra energy
  • In the liquid state, aluminium still has strong electrostatic attraction between the ions and delocalised electrons and so still requires a large amount of energy to boil

Chemistry (29 decks)

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