Physical Unit 2.4: Properties of P3 Elements & their Oxides

Question 1

what is the bonding & structure of Na?

Answer 1

bonding: metallic bonding
structure: giant lattice of +ve metal ions surrounded by -ve delocalised e-s

Question 2

what is the bonding & structure of Mg?

Answer 2

bonding: metallic bonding
structure: giant lattice of +ve metal ions surrounded by -ve delocalised e-s

Question 3

what is the bonding & structure of Al?

Answer 3

bonding: metallic bonding
structure: giant lattice of +ve metal ions surrounded by -ve delocalised e-s

Question 4

what is the bonding & structure of Si?

Answer 4

bonding: covalent
structure: macromolecular
giant lattice

Question 5

what is the bonding & structure in phosphorus?

Answer 5

P4
bonding: covalent
structure: simple molecular

Question 6

what is the bonding & structure in sulfur?

Answer 6

S8
bonding: covalent
structure: simple molecular

Question 7

what is the bonding & structure in chlorine?

Answer 7

Cl2
bonding: covalent
structure: simple molecular

Question 8

what are the observations & equation for the reaction of Na & water?

Answer 8

observations: fizzes, floats, moves on surface, melts, leaves alkaline trail (may catch fire with yellow-orange flame)

equation:
Na + H2O –> NaOH + 1/2H2
pH 14

Question 9

what are the observations & equations for the reaction of Mg & water (l) & (g)?

Answer 9

observations with H2O(l): slow, bubbles on surface of Mg
with H2O (g)/steam: bright white light, forms white solid

equation with H2O(l):
Mg + 2H2O(l) –> Mg(OH)2 + H2
pH 9-10
with H2O(g):
Mg + H2O(g) –> MgO + H2

Question 10

what are the observations & equations for the reaction of Cl2 & water (with & without sunlight)?

Answer 10

observations without sunlight: nvc, if add UI paper, turns from red to white
with sunlight: bubbles

equation without sunlight:
Cl2 + H2O –> HClO + HCl
with sunlight:
2Cl2 + 2H2O –> O2 + 4HCl

Question 11

what are the observations & equation for the reaction of Na & oxygen?

Answer 11

observations: yellow-orange flame, white solid formed

equation:
2Na + 1/2 O2 –> Na2O

Question 12

what are the observations & equation for the reaction of Mg & oxygen?

Answer 12

observations: bright white light, white solid forms

equation:
Mg + 1/2 O2 –> MgO

Question 13

what are the observations & equation for the reaction of Al & oxygen?

Answer 13

observations: bright white light, white solid forms

equation:
2Al + 3/2 O2 –> Al2O3

Question 14

what are the observations & equation for the reaction of Si & oxygen?

Answer 14

observations: bright white light, white solid forms

equation:
Si + O2 –> SiO2

Question 15

what are the observations & equation for the reaction of phosphorus & oxygen?

Answer 15

observations: bright white light, white solid forms

equation:
P4 + 5O2 –> P4O10

Question 16

what are the observations & equation for the reaction of sulfur & oxygen?

Answer 16

observations: blue flame, colourless gas forms

equation:
S + O2 –> SO2

Question 17

what is the structure of Na2O?

Answer 17

ionic
Na+ & O2- ions

Question 18

what is the structure of MgO?
& compare the mp of MgO with Na2O

Answer 18

ionic
Mg2+ & O2- ions
higher mp than Na2O as Mg2+ ions are smaller & have higher charge than Na+ ions

Question 19

what is the structure of Al2O3?

Answer 19

ionic but w large degree of covalent character as Al3+ is small & highly charged

Question 20

what is the structure of SiO2?

Answer 20

covalent macromolecule

Question 21

what is the structure of P4O10?

Answer 21

covalent molecular

Question 22

what is the structure of SO2?

Answer 22

covalent molecular

Question 23

what is the structure of SO3?

Answer 23

covalent molecular

Question 24

describe what happens when Na2O reacts with water, give the equations & pH of the solution formed

Answer 24

what happens: dissolves then O2- ions react

equations:
Na2O + H2O –> 2NaOH
O2- react with water: O2- + H2O –> 2OH-

pH: 14

Question 25

describe what happens when MgO reacts with water, give the equation & pH of the solution formed

Answer 25

what happens: slightly soluble, few O2- ions equations: MgO + H2O --> Mg(OH)2 O2- + H2O --> 2OH- fewer O2- than Na2O so less alkaline pH: 9-10

Question 26

describe what happens when Al2O3 reacts with water, give the equation & pH of the solution formed

Answer 26

what happens: insoluble due to high lattice enthalpy equations: n/a pH: 7 (pH of water bc insoluble)

Question 27

describe what happens when SiO2 reacts with water, give the equation & pH of the solution formed

Answer 27

what happens: insoluble due to v many v strong covalent bonds needs lots of heat energy to break equations: n/a pH: 7

Question 28

describe what happens when P4O10 reacts with water, give the equation & pH of the solution formed

Answer 28

what happens: violent reaction equations: P4O10 + 6H2O --> 4H3PO4 strong acid, fully dissociates pH: 0

Question 29

describe what happens when SO2 reacts with water, give the equation & pH of the solution formed

Answer 29

what happens: dissolves & reacts equations: SO2 + H2O --> H2SO3 weak acid pH: 3

Question 30

describe what happens when SO3 reacts with water, give the equation & pH of the solution formed

Answer 30

what happens: violent reaction equations: SO3 + H2O --> H2SO4 strong acid, fully dissociates pH: 0

Question 31

how does Na2O react with acids & alkalis & what is the nature of the oxide?

Answer 31

reaction with acids: Na2O + 2H+ --> 2Na+ + H2O with alkalis: n/a nature of oxide: basic

Question 32

how does MgO react with acids & alkalis & what is the nature of the oxide?

Answer 32

reaction with acids: MgO + 2H+ --> Mg2+ + H2O with alkalis: n/a nature of oxide: basic

Question 33

how does Al2O3 react with acids & alkalis & what is the nature of the oxide?

Answer 33

reaction with acids: Al2O3 + 6H+ --> 2Al3+ + 3H2O Al2O3 + 6H+ + 9H2O --> 2[Al(H2O)6]3+ with alkalis: Al2O3 + 2OH- + 3H2O --> 2[Al(OH)4]- nature of oxide: amphoteric

Question 34

how does SiO2 react with acids & alkalis & what is the nature of the oxide?

Answer 34

reaction with acids: n/a with alkalis: SiO2 + 2OH- --> SiO32- + H2O nature of oxide: acidic

Question 35

how does P4O10 react with acids & alkalis & what is the nature of the oxide?

Answer 35

reaction with acids: n/a with alkalis: P4O10 + 12OH- --> 4PO43- + 6H2O nature of oxide: acidic

Question 36

how does SO2 react with acids & alkalis & what is the nature of the oxide?

Answer 36

reaction with acids: n/a with alkalis: SO2 + 2OH- --> SO32- + H2O nature of oxide: acidic

Question 37

how does SO3 react with acids & alkalis & what is the nature of the oxide?

Answer 37

reaction with acids: n/a with alkalis: SO3 + 2OH- --> SO42- + H2O nature of oxide: acidic

Question 38

what is the structure of phosphoric(V) acid & its oxo-anion?

Answer 38

see booklet tetrahedral 109.5 in reality all P-O bonds are the same length in phosphate ions due to delocalisation (similar to in benzene)

Question 39

what is the structure of sulfuric(IV) acid & its oxo-anion?

Answer 39

see booklet 107 pyramidal

Question 40

what is the structure of sulfuric(VI) acid & its oxo-anion?

Answer 40

see booklet 109.5 tetrahedral