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Chemistry > Periodicy > Flashcards

Periodicy Flashcards

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1
Q

Describe atomic radius across period 3.

A

Nuclear charge increases but shielding stays the same. Atomic radius decreases as the attraction between nucleus and outer electrons becomes greater.

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2
Q

Explain why magnesium has a greater melting point than sodium.

A

Magnesium has 2 delocalised electrons per atom whilst sodium only has 1 therefore the metallic bonding is stronger.

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3
Q

Explain why aluminium has a greater Melting point than magnesium.

A

Aluminium has 3 delocalised electrons per atom whereas magnesium only has 2 so the metallic bonding is greater.

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4
Q

Explain the trend in melting point of silicone and what causes this.

A

Higher melting point than expected.

Silicone is a giant covalent macromolecule so had 4 covalent bonds which must be broken.

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5
Q

Explain the trend In melting point of phosphorus.

A

Phosphorus is a simple covalent molecule which exists as P4. It has a very low melting point as only weak intermolcular van der waals forces must be overcome.

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6
Q

Explain the melting point of sulphur.

A

Sulphur exists as S8. Therefore there are more electrons that in P4 and more van der waals forces which must be overcome.

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7
Q

Explain the melting point of Cl.

A

Exists as a diatomic molecules with van der waals forces between atoms that must be overcome.

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8
Q

Explain the melting point of Ar.

A

Ar is a single monotomic has. However there are still van der waals forces between each atom which must be overcome.

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9
Q

Which element in period 3 has a lower boiling point than expected and why ?

A

Silicone.

Vaporisation occurs after the covalent bonds have been broken. Si2+ and Si3+ ions are formed.

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10
Q

Explain the conductivity of sodium.

A

Each sodium ions has 1 delocalised electrons capable of carrying charge.

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11
Q

Explain the conductivity of magnesium.

A

Each magnesium ion has 2 delocalised electrons capable of carrying the charger. Greater than sodium.

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12
Q

Explain the conductivity of aluminium.

A

Each ion has 3 delocalised electrons per ion capable of carrying charge.
Greater than sodium and magnesium.

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13
Q

Explain the conductivity of silicone.

A

Silicone has no delocalised electrons but is a giant covalent macromolecule which can become a semi-conductive metallic.
Lower than aluminium and magnesium.

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14
Q

Explain the conductivity of P, S, Cl, Ar.

A

No delocalised electrons so don’t conduct.

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15
Q

State the general trend in ionisation energies across period 3.

A

Increases
Nuclear charge increases but shielding stays the same. So there is a greater attraction between the nucleus and electrons meaning more energy is required to overcome this attraction.
Atomic radius decreases.

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16
Q

Explain the elements that derive from the general trend of first ionisation energies across period 3 and why.

A

Al - lower than expected. Electron is removed from the 3P orbital not the 3S which is a dumbbell shape and therefore further from the nucleus.

S- lower than expected. Electron pairs formed in the 3P orbital so the repulsion makes it easier for an electron to be removed.

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17
Q

Describe the trend in electronegativity across period 3.

A

Increases.
Greater nuclear charge
Same shielding
Decreasing atomic radius

Easier for nucleus to attract bonding pair of electrons in the covalent bond.

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18
Q

What is the formula for the reaction between sodium and water ?

A

2Na + 2H2O - 2NaOH + H2

Sodium hydroxide and hydrogen gas produced.

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19
Q

Why and where is sodium stored.

A

In liquid paraffin oil to prevent reaction with air.

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20
Q

What are the observations when sodium reacts with water.

A

Floats - less dense than water.
Moving around the surface of water to form sphere. The reaction is highly ectothermic so the surface of sodium is melted.
Effervescence as gas is given off.
Ph 13-14 produced.

21
Q

What is the resultant Ph of the solution created when sodium reacts with water.

A

13-14

22
Q

Write the equation for the reaction between magnesium and stream.

A

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

23
Q

What are the observations of the reactions of magnesium with water.

A

Effervescence as gas is given off.
White flame produced.
White magnesium oxide powder precipitate formed.
Ph 10

24
Q

Write the equation for the reaction of chlorine with water.

A

Cl2(as) + H2O— HClO + HCl

25
Q

Write the equation and state the observations for the reaction of oxygen with sodium.

A

4Na(s) + O2(g) - 2Na2O(s)
Yellow flame
White solid precipitate formed.

26
Q

Write the equation and state the observations for the reaction of oxygen with magnesium

A

2Mg(s) + O2(g) - 2MgO(s)
White flame
White precipitate formed.

27
Q

Write the equation and state the observations for the reaction of oxygen with aluminium.

A

4Al(s) +3O2(g) - 2Al2O3(s)
White flame
White precipitate

28
Q

Write the equation and state the observations for the reaction of oxygen with silicone.

A

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

White precipitate

29
Q

Write the equation and state the observations for the reaction of pxygen with phosphorus.

A

4P(s) +5O2(g) - P4O10(s)
White smoke
Ignited spontaneously in air

30
Q

Write the equation and state the observations for the reaction of oxygen with sulphur.

A

S(s) + O2 - S02(g)
Blue flame.
Can further react with a catalyst:
So2 + 1/2O2 - SO3(g)

31
Q

What type of reactions occur when the period 3 elements react with oxygen

A

Redox

32
Q

Describe the melting point of sodium oxide and give its formula based on bonding.

A

Ionic bonding. Therefore there is a high melting point as a lot of thermal energy must be used to overcome the attraction between oppositely charged ions in the giant ionic lattice.

33
Q

Describe the melting point of magnesium oxide and give its formula based on bonding.

A

Higher than sodium. Giant ionic lattice with greater charge density than sodium therefore more thermal energy required to overcome stronger forces of attraction between oppositely charged ions.

34
Q

Describe the melting point of aluminium oxide and give its formula based on bonding.

A

Mostly ionic with covalent character so still has a high melting point.
Slightly lower than magnesium oxide due to covalent character.

35
Q

Describe the melting point of silicone oxide and give its formula based on bonding.

A

Giant covalent structure therefore it has a high melting point as 4 strong covalent bonds must be broken per each Si atom.
Lower than aluminium oxide.

36
Q

Describe the melting point of phosphorus oxide and give its formula based on bonding.

A

This is a simple covalent structure so only intermolcular can der waals and dipole dipole forces of attraction must be overcome.
Lower than silicone oxide.

37
Q

Describe the melting point of silicone dioxide and give its formula based on bonding.

A

Simple covalent. Only van der waals must be overcome.

Lower than Phosphorus oxide.

38
Q

Describe the melting point of sulphur trioxide and give its formula based on bonding.

A

Must overcome van der waals forces. But greater amount of electrons and surface area than sulphur dioxide therefore more heat energy required as there are more van der waals.

39
Q

Write the formula and give the observations when water reacts with oxides of sodium.

A

Na2O(s) + H2O(l) - 2NaOH(at)
Ph 13-14
Alkaline produced because OH- ion present.

40
Q

Write the formula and give the observations when water reacts with oxides of magnesium.

A

MgO(s) + H2O(l) - Mg(OH)2(s)
PH10
Alkaline produce because OH- ions present.

41
Q

Write the formula and give the observations when water reacts with oxides of aluminium.

A

Insoluble in water so Ph remains at 7

42
Q

Write the formula and give the observations when water reacts with oxides of silicone.

A

Insoluble in water so Ph remains at 7

43
Q

Write the formula and give the observations when water reacts with oxides of phosphorus.

A

P4O10(s) + 6H2O(l) - 4H3PO4(aa)
Ph 0-1
Acidic Ph because H+ ions present

44
Q

Write the formula and give the observations when water reacts with oxides of sulphur dioxide

A

S02(g) +H2O(l) - H2SO3(aq)
Ph 2-3
Acidic because H+ ions present.

45
Q

Write the formula and give the observations when water reacts with oxides of sulphur trioxide.

A

SO3(g) + H2O(l) - H2SO4(at)
Ph0-1
Acidic because H+ ions present

46
Q

What is an amphoteric oxide ?

A

One which can react with acids and bases

47
Q

What is an oxide which can react with both acids and bases called ?

A

Amphoteric oxide

48
Q

Why does aluminium not conduct electricity.

A

It is conducted by an oxide layer.

Chemistry (27 decks)

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