Reactivity of metals (chemical changes)

Question 1

What are oxidation and reduction reactions?

Answer 1

• In oxidation reactions, a substance often gains oxygen. In reduction reactions, a substance often loses oxygen. Oxidation and reduction always occur together.

Question 2

What is produced when a metal reacts with oxygen?

Answer 2

• Metals react with oxygen to form metal oxides. For example, when magnesium is burned in air it reacts with oxygen to form magnesium oxide. The magnesium gains oxygen in the reaction, so it is oxidised.

Question 3

What happens when metal atoms react?

Answer 3

• **When metal atoms react, their atoms lose electrons to form positive ions. Some metals lose electrons more easily that others. The more easily a metal atom loses electrons, the more reactive it is. **

Question 4

What is produced when metals react with acids?

Answer 4

• Metals react with acids to produce a metal salt and hydrogen.

Question 5

What are some examples of very reactive metals?

Answer 5

• Lithium, sodium and potassium are very reactive metals – they react vigorously with water to produce a metal hydroxide solution and hydrogen. These metals are placed at the top of the reactivity series.

Question 6

What are some examples of fairly reactive metals?

Answer 6

• Calcium, magnesium, zinc and iron are fairly reactive –they react quickly with acids andd slowly with water.

Question 7

What are some examples of very unreactive metals?

Answer 7

• Very unreactive metals, like copper and gold, do not react with acids or water and are placed at the bottom of the periodic table.

Question 8

What occcurs in a displacement reaction?

Answer 8

• In a displacement reaction a more reactive metal will displace a leess reactive metal from a solution of its salt. Magnesium is more reactive than copper, so magnesium will displace copper from a solution of copper sulfate.

Question 9

How are metals extracted?

Answer 9

• The method of extraction of a metal depends on how reactive it is. Unreactive metals (e.g. gold) exist as elements at the Earth’s surface.
• However, most metals are found as metal oxides, or as compounds that can easily be changed into metal oxides.
• Metals that are less reactive than carbon (e.g. iron and lead) can be extracted from their oxides by heating with carbon.
• Metals that are more reactive than carbon (e.g. aluminium) are extracted from molten compounds by electrolysis.