2.4 Properties Of Period 3 Elements And Their Oxides Flashcards

1
Q

Appearance and physical properties of sodium

A

Metallic, shiny, conducts electricity (worst conductor out of the metals)

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2
Q

Reaction of sodium with acid?

A

Na + acid —> H2 + salt

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3
Q

Reaction of sodium with cold water - equation and observations

A

Vigorous reaction, floats on water,fizzes melts due to -△H of the reaction. NaOH is pH 13-14.

2Na + 2H2O —> 2NaOH + H2

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4
Q

Reaction of sodium with oxygen (equation and observation)?

A

Bright yellow flame, forms white powder of Na2O

2Na + 1/2 O2 —> Na2O

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5
Q

Appearance and physical properties of magnesium

A

Metallic, shiny, conducts electricity (between Na and Al in terms of how well it does)

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6
Q

Reaction of Mg with cold water (observation and equation)

A

Very slow reaction. pH = 10 as Mg(OH)2 is sparingly soluble

Mg + 2H2O —> H2 + Mg(OH)2

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7
Q

Reaction of Mg with steam (observation and equation)? I’m

A

Much faster

Mg + H2O —> MgO + H2

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8
Q

Reaction of Mg with oxygen (observation and equation)?

A

Bright white flame, forms white powder of MgO

2!g + O2 —> 2MgO

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9
Q

Appearance and physical properties of aluminium?

A

Metallic, shiny best conductor of electricity in period 3

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10
Q

Reaction of Al with cold water?

A

No readtion

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11
Q

Reaction of Al with oxygen (observation and equation)?

A

Heat and lower into jar of O2–> bright flame, forms white powder

4Al + 3O2 —> 2Al2O3

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12
Q

Why is aluminium considered unreactive even through the metal itself is reactive

A

Covered by Al2O3 from where oxygen has oxidised the surface of the Al. Al2O3 is unreactive. Makes it useful for saucepans, window frames etc.

If Al2O3 is scratched off, Al reacts rapidly with air to form a new coat

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13
Q

Appearance and physical properties of silicon

A

Semimetal (metalloid), semiconductor (conducts electricity to an extent and in certain conditions)

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14
Q

Reaction of silicon with oxygen (observations and equations)?

A

Heat strongly

Si + O2 —> SiO2 (white powder)

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15
Q

Appearance and physical properties of phosphorus

A

Non-metal, low m.p. And b.p. Does not conduct electricity

Red phosphorus as a crystal structure
White phosphorus as P4

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16
Q

Reaction of phosphorus in excess oxygen (observations and equations)?

A

Red P needs to be heated significantly first, white P ignites spontaneously in air
Phosphorus pentoxide (white crystalline solid) formed

4P + 5O2 —> P4O10

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17
Q

Reaction of phosphorus in limited oxygen (observations and equation)?

A

Incomplete combustion: colourless liquid phosphorus trioxide s formed

4P + 3O2 —> P4O6

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18
Q

Appearance and physical properties of sulfur?

A

Non-metal, low mp and bp, does not conduct electricity

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19
Q

Reaction of sulfur with oxygen (observations and equation)?

A

Need to heat and lower into a jar of oxygen. Colourless gas sulfur dioxide formed. Some SO3 also formed.

S+O2–> SO2

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20
Q

What are the different types of structure and bonding displayed by the period 3 oxides?

A

Na ionic lattice
Mg ionic lattice
Al ionic lattice with covalent character; Al3+ distorts O2- electron cloud
Si giant covalent
P simple molecular covalent
S simple molecular covalent

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21
Q

What is the trend in melting points for period 3 oxides (state highest and lowest and why and draw graph)?

22
Q

Which period 3 oxides are basic

A

Na2O and MgO

23
Q

Reaction of Na oxide with water? pH?

A

Na2O + H2O —> 2Na+ + 2OH-; pH=14

24
Q

Reaction of Mg oxide with water? pH?

A

MgO + H2O —> Mg2+ + 2OH- ⇌ Mg(OH)2

pH = 9-10 as Mg(OH)2 is sparingly soluble

25
What are the products if Na2O and MgO are reacted with acid?
Salt and water only
26
Is aluminium oxide acidic or basic
It is amphoteric; can act as either an acid or a base
27
Is aluminium oxide soluble
Not in water
28
Reaction of aluminium oxide with HCl?
Al2O3 + 6HCl —> 3H2O + 2AlCl3
29
Reaction of aluminium oxide with NaOH?
Al2O3 + 2NaOH + 3H2O —> 2NaAl(OH)4 ; sodium aluminate is formed
30
Is silicon dioxide soluble in water
No
31
In what conditions will silicon dioxide act as an acid
Reacts as a weak acid with a strong base
32
Reaction of silicon dioxide with hot, conc NaOH?
SiO2 + 2NaOH —> H2O + Na2SiO3 - sodium silicate
33
How is silicon dioxide used in the production of Fe?
SiO2 + CaO —> CaSiO3 - calcium silicate
34
Reaction of phosphorus pentoxide with water? pH?
P4O10 + 6H2O —> 4H3PO4; pH = 1-2
35
Dissociation of the acid formed (H3PO4)?
H3PO4 —> H+ + H2PO4-
36
Reaction of P4O10 with NaOH?
3NaOH + H3PO4 —> Na3PO4 + 3H2O
37
Reaction of SO2 with water? pH?
SO2 + H2O —> H2SO3 ; weak acid —> pH = 2-3
38
Reaction of SO3 with water? pH?
SO3 + H2O —> H2SO4 strong acid —> pH = 0-1
39
Reaction of SO2 with NaOH? (2 stages)
SO2 + NaOH —> NaHSO3 NaHSO3 + NaOH —> Na2SO3 + H2O
40
How can flue gases be removed by CaO?
CaO + SO2 —> CaSO3 (calcium sulfite)
41
Draw the structure of H3PO4?
Slide 84
42
How many electrons does P have in its outer shell in H3PO4?
10
43
What is the shape and bonding in PO43-?
Electrons delocalise to give tetrahedral structure with 109.5 bond angle. Each P-O bond is the same length
44
Draw the structure and bonding of H2SO4?
Slide 90
45
What is the structure, bonding and shape of SO4 2-?
Electrons delocalise —> tetrahedral with 109.5 bond angle. Each S-O bond is the same
46
What is the structure, bonding and shape of SO3 2-?
Bond angle = 106 (Trigonal pyramid shape), each S-O bond is the same, S has one lone pair of electrons
47
Uses of MgO
Additive for cattle feed
48
How useful is Al2O3?
Oxide layer on Aluminium makes it very useful as it is unreactive and returns quickly if it is scratched off
49
Uses of SO2
Reactant in contact process (making H2SO4)
50
Would lithium oxide or sodium oxide have a higher melting point? Why?
Li2O has a higher m.p., since Li+ is a smaller ion than Na+, so the O2- and Li+ charge centres are closer together and there is a greater electrostatic force of attraction between the oppositely charged ions