22.1 Reactions of period 3 elements

Question 1

Properties of the first 3 period 3 elements

Sodium, magnesium and aluminium

Answer 1

They are metallic

So are shiny when first exposed to air, conduct electricity, and react with dilute acids to give hydrogen and salts

Question 2

Describe the conduction of silicon

Answer 2

. Metalloid so conducts electricity to some extent which is useful

Question 3

Phosphorus, sulfur and chlorine properties

Answer 3

. Non-metals
They don’t conduct electricity and have low melting and boiling points

Question 4

Argon properties

Answer 4

It’s a noble gas, chemically unreactive

Question 5

What two metals from period 3 react with water

Answer 5

Sodium and magnesium

Question 6

How does sodium react with water

Answer 6

. Vigorous reaction
. Sodium floats on top of the water and fizzes rapidly
. It melts because of the heat energy released by the reaction

. A strongly alkaline solution of sodium hydroxide is formed

Question 7

The equation of sodium and water

Answer 7

2Na(s) +2H20(l) –> 2NaOH(aq) + H2(g)

Question 8

How does magnesium react with water

Answer 8

. It is a very slow reaction at room temperature
. Only a few bubbles of hydrogen are formed after days

The resulting solution is less alkaline than with sodium because magnesium hydroxide is only sparingly soluble (PH 10)

Question 9

How can you make the reaction between magnesium and water faster

What is the reaction for this reaction, and what type of reaction is it

Answer 9

. React magnesium with steam

Mg(s) + H20(g) –>
MgO + H2(g)

Its a redox reaction as the oxidation state of the metal increases from 0 to 2+ and that of the hydrogen decreases from 1+ to 0

Question 10

Equation of magnesium with liquid water

Answer 10

Mg(s) + 2H20(l) —>
Mg(OH)2(aq) + H2(g)

Question 11

How do period 3 elements react with oxygen

Eg Sodium

Answer 11

All elements in period 3 are relatively reactive so directly react with it.

2Na(s) +1/2O2(g) –>
Na2O(s)

Sodium burns brightly in air with a yellow flame to form white sodium oxide

Question 12

magnesium + oxygen

Answer 12

2Mg(s) + O2(g) —>
2MgO(s)

It makes magnesium oxide

Question 13

How do magnesium and oxygen react

Answer 13

A strip of magnesium ribbon burns in air with a bright white flame.

It produces a white powder called magnesium oxide

Question 14

How does aluminium react with oxygen

Answer 14

When aluminium powder is heated and then lowered into a gas jar of oxygen, it burns brightly to make aluminium oxide which is a white powder

Question 15

Equation for aluminium and oxygen

Answer 15

4Al(s) + 3O2(g) —> 2Al2O3(s)

Question 16

Aluminium is a reactive metal, so how is it protected from rusting

Everyday uses

Answer 16

. Its oxide forms a strongly bonded protective layer over it which protects it from reacting even further

That’s why aluminium is seen as an unreactive metal and has everyday uses eg saucepan or window frame

Question 17

How does silicon react with oxygen
Give equation

Answer 17

Silicon will also form an oxide if heated strongly in oxygen

Si(s) + O2(g) –> SiO2(s)

Question 18

How does phosphorus react with oxygen

Why is there both red and white phosphorus

Answer 18

. Red phosphorus must be heated before it will react with oxygen
. White phosphorus spontaneously ignites in air and the white smoke of phosphorus pentoxide is given off

Red and white are allotropes of phosphorus- the same element with the particles arranged differently

Question 19

What is the equation for phosphorus and oxygen

What is produced when oxygen supply is limited

Answer 19

4P(s) + 5O2(g) –> P4O10(s)
Makes phosphorus pentoxide

P2O3 phosphorus trioxide is formed

Question 20

How does sulfur react with oxygen

Answer 20

.When sulfur powder is heated and lowered into a glass jar of oxygen
. It burns with a blue flame to form colourless gas sulfur dioxide (and a little sulfur trioxide also forms)

Question 21

Equation of sulfur and oxygen

Answer 21

S(s) + O2(g) —> SO2(g)

Question 22

What occurs in all the redox reactions of period 3 elements and oxygen

Answer 22

. The oxidation state of the period 3 element increases so that of oxygen decreases from O to -2 in each case

The oxidation number of the period 3 element increases across the period