Properties of Period 3 elements and their oxides

Question 1

Why is less energy required to ionise sodium?

Answer 1

It is more reactive

Question 2

What are the oxides of all period 3 metals?

Answer 2

Na2O - ionic
MgO - ionic
Al2O3 - ionic with covalent character
SiO2 - Macromolecular
P4O10 - Simple covalent
SO2 - Simple covalent
SO3 - Simple covalent

Question 3

How do ionic oxides react with water?

Answer 3

Na2O + H2O -> 2NaOH
MgO + H2O -> Mg(OH)2
these reactions form alkaline solutions with pH of around 10-14

Question 4

How do simple covalent oxides react with water?

Answer 4

P4O10 + 6H2O -> 4H3PO4
SO2 + H2O -> H2SO3
SO3 + H2O -> H2SO4

Question 5

What are the examples of neutralisation reactions with basic ionic compounds?

Answer 5

Na2O + 2HCl -> 2NaCl + H2O
MgO + H2SO4 -> MgSO4 + H2O

Question 6

What are examples of neutralisation reactions with acidic covalent oxides?

Answer 6

SiO2 + 2NaOH -> Na2SiO3 + H2O
P4O10 + 12 NaOH -> 4Na3PO4 + 6H2O
SO2 + 2NaOH -> Na2SO3 + H2O
SO3 + 2NaOH -> Na2SO4 + H2O

Question 7

Define amphoteric

Answer 7

A substance with can act as both an acid and a base e.g. aluminium oxide

Question 8

Why is aluminium oxide amphoteric?

Answer 8

It is partially covalent, partially ionic (hence it is also insoluble in water)

Question 9

What are the amphoteric reactions of aluminium oxide?

Answer 9

Al2O3 + 3H2SO4 -> Al2(SO4)3 + 3H2O
Al2O3 + 2NaOH + 3H2O -> 2NaAl(OH)4