period 3

Question 1

Na + Oxygen

Answer 1

4Na + O2 –> 2Na2O
yellow flame
white solid

Question 2

Magnesium + oxygen

Answer 2

2Mg + O2 –> 2MgO
white flame
white solid smoke

Question 3

Aluminium + oxygen

Answer 3

4Al + 3O2 –> 2Al2O3
white flame
white solid smoke

Question 4

Silicon + oxygen

Answer 4

Si + O2 –> SiO2
white flame
white solid smoke

Question 5

Phosphorus + oxygen

Answer 5

4P + 5O2 –> P4O10
white solid
white flame

Question 6

Sulfure + oxygen

Answer 6

S + O2 –> SO2
blue flame
acidic choking gas

Question 7

Ionic Giant Lattice (which metals, what properties)

Answer 7

. Na2O, MgO, Al2O3
. Strong forces of attraction: high mp
.

Question 8

Na2O + H20

Answer 8

. Na2O + H2O –> 2Na+ + 2OH-
. pH 13
. Vigorous exothermic reaction

Question 9

MgO + H2O

Answer 9

. MgO + H2O –> Mg(OH)2
. pH 9
. only slightly soluble in water as its lattice is stronger - fewer free OH- ions produced.

Question 10

Al2O3 + H2O

Answer 10

. Does not dissolve in water
. Due to high ionic lattice strength
. Neutral pH 7

Question 11

SiO2 + H2O

Answer 11

. Does not dissolve in water
. Due to macromolecular structure
. Neutral pH 7

Question 12

P4O10 + H2O

Answer 12

. P4O10 + 6H2O –> 4H3PO4
. pH 0
. Vigorous exothermic reaction

Question 13

SO2 + H2O

Answer 13

. SO2 + H2O –> H2SO3
. pH 3 (weak acid)
. SO2 + H2O –> H+ + HSO3-

Question 14

SO3 + H2O

Answer 14

SO3 + H2O –> H2SO4
. pH 0
. SO3 + H2O –> H+ + HSO4-

Question 15

Magnesium reaction with steam

Answer 15

Mg + H2O –> MgO + H2
. white solid
. Bright white flame

Question 16

Outline an experiment to show that MgO is ionic

Answer 16

Melt it - molten oxide would conduct electricity.

Question 17

Explain why the atomic radii of the elements decrease across Period 3 from sodium to chlorine.

Answer 17

. Number of protons increases

. So attraction between nucleus and electrons increases.

Question 18

Explain why sodium oxide forms an alkaline solution when reacting with water

Answer 18

Has O2- ions

which react with water to form OH- ions

Question 19

Explain why magnesium has a higher melting point than sodium

Answer 19

Mg2+ has a higher charge than Na+

Attracts delocalised electrons more strongly

Question 20

Suggest why silicon dioxide is described as an acidic oxide even though it is insoluble in water.

Answer 20

It reacts with bases.

Question 21

Amphoteric definition

Answer 21

Acts as both an acid and an alkali

Question 22

What metal oxide is amphoteric

Answer 22

Al3O4

Question 23

Al2O3 + NaOH

Answer 23

Al2O3 + 2NaOH + 3H2O –> 2NaAl(OH)4

Question 24

Al2O3 + HCl

Answer 24

Al2O3 + 6HCl –> 2AlCl3 + 3H2O

Question 25

MgO + phosphoric acid

Answer 25

3MgO + 2H3PO4 --> Mg3(PO4)2 + 3H2O