5.1 - Period 3 Elements

Question 1

What observations are there when sodium reacts with water?

Answer 1

It forms a floating molten ball that fizzes due to H₂ gas being produced.

Question 2

What is the equation for sodium reacting with water?

Answer 2

2Na + 2H₂O —-> 2NaOH + H₂

Question 3

What is the pH of the solution formed when sodium reacts with water?

Answer 3

12-14.

Question 4

What observations are there when magnesium reacts with cold water?

Answer 4

There aren’t any observations as the reaction occurs very slowly.

Question 5

What is the equation for magnesium reacting with cold water?

Answer 5

Mg + 2H₂O —-> Mg(OH)₂ + H₂

Question 6

What is the pH of the solution formed when magnesium reacts with cold water?

Answer 6

9-10.

Question 7

What is the equation when magnesium reacts with steam?

Answer 7

Mg + H₂O —-> MgO + H₂

Question 8

What is the equation for sodium reacting with oxygen?

Answer 8

2Na + ½O₂ —-> Na₂O

Question 9

What colour flame is there when sodium reacts with oxygen?

Answer 9

Yellow.

Question 10

What is the equation for magnesium reacting with oxygen?

Answer 10

Mg + ½O₂ —-> MgO

Question 11

What colour flame is there when magnesium reacts with oxygen?

Answer 11

Brilliant white.

Question 12

What is the equation for aluminium reacting in air?

Answer 12

2Al + 1½O₂ —-> Al₂O₃

Question 13

What is the equation for silicon reacting with oxygen?

Answer 13

Si + O₂ —-> SiO₂

Question 14

What is the equation for phosphorus reacting with oxygen?

Answer 14

P₄ + 5O₂ —-> P₄O₁₀

Question 15

What colour flame does phosphorus burn with?

Answer 15

A brilliant white flame.

Question 16

What is the equation for sulphur reacting with air?

Answer 16

S + O₂ —-> SO₂

Question 17

What colour flame does sulphur burn with?

Answer 17

Blue.

Question 18

Which oxides form giant ionic lattices?

Answer 18

Na₂O, MgO and Al₂O₃

Question 19

Which oxides form a macromolecular structure?

Answer 19

SiO₂

Question 20

Which oxides form simple covalent molecules?

Answer 20

P₄O₁₀, SO₂ and SO₃.

Question 21

What is the trend in period three oxide melting points?

Answer 21

The overall trend is that they decrease. However, Na₂O is lower than MgO because Mg²⁺ has a higher charge density than Na⁺.

Question 22

Why does Al₂O₃ have a lower melting point than MgO?

Answer 22

The difference in electronegativity between Al and O and Mg and O is lower. This makes the bond partially covalent.

Question 23

What is the equation for the reaction of P₄O₁₀ with water?

Answer 23

P₄O₁₀ + 6H₂O —-> 4H₃PO₄

Question 24

What is the equation for the reaction between sulphur dioxide and water?

Answer 24

SO₂ + H₂O —-> H₂SO₃

Question 25

Why will sodium and magnesium oxide neutralise acids?

Answer 25

They are basic.

Question 26

What is the equation for the reaction between sodium oxide and HCl?

Answer 26

Na₂O + 2HCl —-> 2NaCl + H₂O

Question 27

Which period three oxides will neutralise bases?

Answer 27

Aluminium, Silicon, Phosphorus and Sulphur Oxides.

Question 28

What is the equation for the reaction of SiO₂ with NaOH?

Answer 28

SiO₂ + 2NaOH —-> Na₂SiO₃ + H₂O

Question 29

What is the equation for the reaction of P₄O₁₀ and NaOH?

Answer 29

P₄O₁₀ + 12NaOH —-> 4Na₃PO₄ + 6H₂O

Question 30

What is the equation for the reaction of sulphur dioxide and NaOH?

Answer 30

SO₂ + 2NaOH —-> Na₂SO₃ + H₂O

Question 31

What is the equation for the reaction of aluminium oxide and sulphuric acid?

Answer 31

Al₂O₃ + 3H₂SO₄ —-> Al₂(SO₄)₃ + 3H₂O

Question 32

What is the equation for the reaction of aluminium oxide with NaOH?

Answer 32

Al₂O₃ + 2NaOH + 3H₂O —-> 2NaAl(OH)₄