Topic 11

Metals

Aim of lesson:• Discuss the reaction of metals with:

– Oxygen– Dilute Acid– Water

• Carry out a reaction to test the reactivity of metals with dilute acid.

Reaction of Metals

• When a metal reacts is loses electrons to form positive ions.

e.g. Mg Mg2+ + 2e-

The metals atoms are oxidised.

These reactions allow metals to be placed in a certain order REACTIVITY SERIES

Metals HIGH in the reactivity series are MORE reactive and so more readily form ions and compounds.

Reactivity Series

• Some metals are more reactive than others.

• The reactivity series places the most reactive metals at the top and the least reactive metals at the bottom.

• We can place metals in order of reactivity by comparing how well they react with other substances e.g.

–Oxygen–Dilute acid –Water

Potassium

Sodium

Lithium

Calcium

Magnesium

Aluminium

Zinc

Iron

Tin

Lead

Hydrogen

Copper

Mercury

Silver

Gold

Platinum

K

Na

Li

Ca

Mg

Al

Zn

Fe

Sn

Pb

H

Cu

Hg

Ag

Au

Pt

most reactive

least reactive

Reacting Metals with Oxygen

• When metals are heated with air they may react with the oxygen present.

• Metal + Oxygen Metal oxide

• Some metals react vigorously with oxygen and burn fiercely, some react more slowly and others do not react at all!

ExperimentAim: To investigate the reactions of

magnesium and copper when burned in a plentiful supply of oxygen.

Method:

Potassium permangante

Mineral wool

Heat Heat

Magnesium or Copper

Pyrex test tube

Metal Observation

Magnesium

Copper

Conclusion: Magnesium is more reactive than copper.

Results:

Metals reacting with oxygen

Formulae Equations

Sodium + oxygen sodium oxide

Magnesium + oxygen magnesium oxide

Mg + O22 2 MgO

Potassium + oxygen Potassium oxide

Na + O2Na2O24

K + O2 K2O4 2

Reacting metals with dilute acid

• Some metals react with dilute acids to produce salts and hydrogen.

Metal + Acid Salt + Hydrogen

ExperimentAim: To investigate the reaction of different

metals with acid.

Method:

Results:

Magnesium reacts vigorously with acid.

Copper does not react with acid.

Metals above hydrogen in the ECS react with acids to produced hydrogen gas, but metals below hydrogen do not react with acids.

Metal + Acids Salt + Hydrogen

Metals Reacting with Acid

Magnesium + HCl

Mg + HCl

Potassium + HCl Potassium chloride + H2

Magnesium chloride + H2

MgCl2 + H2

K + HCl

Aluminium + HCl Aluminium chloride + H2

Al + HCl AlCl3 + H2

2

KCl + H222 2

3 1.5

6 3Al + HCl AlCl3 + H2or

Reacting Metals with Water• Some metals react with water and displace

hydrogen to give an alkaline solution.

• Metal + Water Metal hydroxide + hydrogen

• Again, some metals react more vigorously than others.

Potassium, sodium and lithium react so violently with water that they must be stored in oil, to prevent them reacting with moisture in the air!

• Conclusion:– When metals react with water an alkali is produced.

Hydrogen gas is also formed.

Metal + Water Metal Hydroxide + Hydrogen

Metals Reacting with water

Lithium + H2O

Li + H2O

Sodium + H2O Sodium hydroxide + Hydrogen

Lithium hydroxide + Hydrogen

LiOH + H2

Magnesium + H2O

Mg + H2O

2 2 2

Na + H2O NaOH + H22 2 2

Magnesium hydroxide + Hydrogen

Mg(OH)2 + H22

Remember!

Metal + Oxygen Metal oxide

Metal + Acid Salt + Hydrogen

Metal + Water Metal hydroxide + hydrogen

Quick Quiz1. Where can the most reactive metals be

found in the reactivity series?

2. What is produced when metals react with oxygen?

3. What is produced when metals react with acid?

Most reactive metals at top, least reactive metals at the bottom.

Metal oxide

Salt and hydrogen