Properties of Period 3 Elements

Question 1

Give the equation for the reaction of sodium with water

Answer 1

2Na(s) + 2H2O(l) –> 2NaOH(aq) + H2(g)

Question 2

Give the equation for Magnesium with water

Answer 2

Mg(s) + 2H2O(l) –> Mg(OH)2(aq) + H2(g)

Question 3

Give the equation for Magnesium with steam

Answer 3

Mg(s) + H2O(g) –> MgO(s) + H2(g)

Question 4

Give the equation for chlorine forming HClO

Answer 4

Cl2(g) + H2O(l) –> HClO(aq) + HCl(aq)

Question 5

Give the equation for chlorine forming HCl

Answer 5

2Cl2(g) + 2H2O(l) –> 4HCl(aq) + O2(g)

Question 6

Give the equation for sodium with oxygen

Answer 6

2Na(s) + 1/2O2(g) –> Na2O(s)

Question 7

Give the equation for magnesium with oxygen

Answer 7

2Mg(s) + O2(g) –> 2MgO(s)

Question 8

Give the equation for aluminium with oxygen

Answer 8

4Al(s) + 3O2(g) –> 2Al2O3(s)

Question 9

Give the equation for silicon with oxygen

Answer 9

Si(s) + O2(g) –> SiO2(s)

Question 10

Give the equation for phosphorus with oxygen

Answer 10

P4(s) + 5O2(g) –> P4O10(s)

Question 11

Give the equation for sulfur with oxygen

Answer 11

S(s) + O2(g) –> SO2(s)

Question 12

Why does MgO have the highest melting point of all P3 oxides?

Answer 12

• MgO has ionic bonds
• strong electrostatic attraction between oppositely charged ions
• these require alot of energy to overcome

Question 13

Why does Al2O3 have more covalent character that MgO?

Answer 13

• the Al3+ ion is smaller than the Mg2+ ion
• meaning the Al3+ ions is more polarising than the Mg2+ ion
• distorting the electron cloud around O2- ion more.

Question 14

Give the equation for sodium oxide with water

Answer 14

Na2O(s) + H2O(l) –> 2Na+(aq) + 2OH-(aq)

Question 15

Give the equation of magnesium oxide with water

Answer 15

MgO(s) + H2O(l) –> Mg(OH)2(aq)

🔑 point - magnesium hydroxide is only sparingly soluble so is only weakly alkaline.

Question 16

What are the 2 insoluble oxides

Answer 16

Aluminium Oxide and Silicon dioxide so no reaction occurs.

Question 17

What is the PH when aluminium oxide and silicon dioxide are added to water.

Answer 17

7
There is no reaction to make the water acidic or alkaline

Question 18

What is the equation for phosphoric acid with water

Answer 18

P4O10(s) + 6H2O(l) –> 4H3PO4(aq)

Question 19

What is the equation for sulfur dioxide in water

Answer 19

SO2(g) + H2O(l) –> H2SO3(aq)
*Sulfurus acid

Question 20

What is the equation for sulfur trioxide with water

Answer 20

SO3(g) + H2O(l) –> H2SO4(aq)

Question 21

Give the equation for sodium oxide with H2SO4

Answer 21

Na2O(s) + H2SO4(aq) –> Na2SO4(aq) + H2O(l)

Question 22

Give the equation for magnesium oxide with HCl

Answer 22

MgO(s) + 2HCl(aq) –> MgCl2(aq) + H2O(l)

Question 23

What is it meant by amphoteric?

Answer 23

It can act as an acid or base

Question 24

Give an example of an amphoteric oxide

Answer 24

Aluminium oxide

Question 25

Give the equation for aluminium oxide when it acts as a base

Answer 25

Al2O3(s) + 6HCl(aq) --> 2AlCl3(aq) + 3H2O(l)

Question 26

Give the equation for aluminium oxide when it acts as a base

Answer 26

Al2O3(s) + 2NaOH(aq) + 3H2O(l) --> 2NaAl(OH)4(aq)

Question 27

Give the equation for phosphoric acid with sodium hydroxide

Answer 27

H3PO4(aq) + 3NaOH(aq) --> Na3PO4(aq) + 3H2O(l)

Question 28

Give the ionic equation for the reaction of phosphorus(V) oxide with an excess of sodium hydroxide solution

Answer 28

P4O10 + 12OH- --> 4PO43- + 6H2O

Question 29

Give the equation for sulfur dioxide in solution

Answer 29

SO2(aq) + 2NaOH(aq) --> Na2SO3(aq) + H2O(l)

Question 30

Give the equation for phosphoric oxide with sodium oxide

Answer 30

P4O10 + 6Na2O --> 4Na3PO4(aq)

Question 31

Give the equation for phosphoric oxide with magnesium oxide

Answer 31

P4O10 + 6MgO --> 2Mg3(PO4)2(aq)

Question 32

Explain using an equation why silicon oxide is classified as an acidic oxide

Answer 32

SiO2 + 2NaOH --> Na2SiO3 + H2O