3.2.4 Properties of Period 3 elements and their oxides

Question 1

Reaction of Na with water + pH

Answer 1

2Na + H2O –> 2NaOH + H2
pH: 14

Question 2

Reaction of Mg with water (l) + pH

Answer 2

Mg + 2H2O –> Mg(OH)2 + H2
pH: 10

Question 3

Reaction of Mg with water (g) + observations

Answer 3

Mg + H2O –> MgO + H2
Bright white light, white solid

Question 4

Why is sodium more reactive than magnesium

Answer 4

It only has to lose one electron to form its ion, whereas Mg has to lose two, so less energy is needed to ionise Na

Question 5

Formation of sodium oxide

Answer 5

2Na + O2 –> Na2O

Question 6

Formation of magnesium oxide

Answer 6

2Mg + O2 –> 2MgO

Question 7

Formation of aluminium oxide

Answer 7

4Al + 3O2 –. 2Al2O3

Question 8

Formation of phosphorus oxide

Answer 8

P4 + 5O2 –> P4O10

Question 9

Formation of silicon dioxide

Answer 9

Si + O2 –> SiO2

Question 10

Formation of sulfur (IV) oxide

Answer 10

S + O2 –> SO2

Question 11

Formation of sulfur (VI) oxide

Answer 11

2S + 3O2 –> 2SO3

Question 12

Trend in reaction of period 3 elements with oxygen

Answer 12

Generally decreases across the period

Question 13

Ionisation energy trend across period 3

Answer 13

Generally decreases, however, two exceptions. Aluminium because the 3p sub shell is of higher energy than the 3s sub shell. Sulfur as 3 the 3p4 paired electrons repel, making them easier to lose.

Question 14

Melting point trend in period 3

Answer 14

Na to Al - metallic elements, along they have more delocalised electrons so stronger attraction between sea of delocalised electrons and positive metal ions

Si - giant molecular structure with covalent bonds, so high melting point

P - simple molecular so has weak VDWs

S - simple molecular, but S8 is larger than P4 so has stronger VDWs

Cl - simple molecular and small so low melting point

Ar - single atom, very few VDWs

Question 15

Formation of SO3 from SO2 and a catalyst

Answer 15

SO2 + V2O5 –> SO3 + V2O4
V2O4 + 1/2 O2 –> V2O5

Question 16

Reaction of sodium oxide with acid

Answer 16

Na2O + 2HCl –> 2NaCl + H2O

Question 17

Reaction of magnesium oxide with acid

Answer 17

MgO + H2SO4 –> MgSO4 + H2O

Question 18

Reaction of aluminium oxide with acid

Answer 18

Al2O3 + 6HCl –> 2AlCl3 + 3H2O

Question 19

Reaction of aluminium oxide with a base

Answer 19

Al2O3 + 2NaOH + 3H2O –> 2Na+ + 2Al(OH)4-

Question 20

Reaction of phosphorus oxide with a base

Answer 20

P4O10 + 12NaOH –> 4Na3PO4 + 6H2O

Question 21

Reaction of silicon dioxide with a base

Answer 21

SiO2 + 2NaOH –> Na2SiO3 + H2O

Question 22

Reaction of sulfur (IV) oxide with a base

Answer 22

SO2 + 2NaOH –> Na2SO3 + H2O

Question 23

Reaction of sulfur (VI) oxide with a base

Answer 23

SO3 + 2NaOH –> Na2SO4 + H2O

Question 24

What property allows aluminium to react with both acids and bases

Answer 24

Amphoteric

Question 25

Reaction of sodium oxide with water + pH

Answer 25

Na2O + H2O -> 2NaOH pH = 14

Question 26

Reaction of magnesium oxide with water + pH

Answer 26

MgO + H2O -> Mg(OH)2 pH = 10

Question 27

Reaction of sodium (IV) oxide with water + pH

Answer 27

SO2 + H2O -> H2SO3 pH = 4

Question 28

Reaction of sulfur (VI) oxide with water + pH

Answer 28

SO3 + H2O -> H2SO4 pH = 0

Question 29

Reaction of phosphorus oxide with water + pH

Answer 29

P4O10 + 6H2O -> 4H3PO4 pH = 1

Question 30

Why does SiO2 not react with water

Answer 30

Due to its strong covalent bonds

Question 31

Why does AL2O3 not react with water

Answer 31

Too insoluble due to strong ionic bonding

Question 32

What type of bonding is aluminium oxide

Answer 32

Ionic with covalent character