2.3.2Chemical Bonding, Application Of Chemical Reactions and Organic Chemistry
Native Metals
5 min read 6 parts Lesson 26 of 54 1 quiz
Section 1 of 6Native metals
Uncombined elements
- Uncombined elements Very unreactive metals do not readily react with oxygen, water or other substances,
- so they stay as the pure element in the ground.
- These are called native metals; gold and silver are the usual examples.
No chemical extraction needed
- No chemical extraction needed Native metals can be mined directly,
- because they are not locked up in compounds,
- although they may still need separating from rock.
Reason
- Reason Their chemical stability means they have little tendency to lose electrons and form compounds.
Section 2 of 6Reactivity decides the method
1Very reactive metals
- Very reactive metals Metals above carbon,
- such as potassium, sodium, calcium, magnesium and aluminium, hold on to oxygen too strongly for carbon to remove it.
2Electrolysis
- Electrolysis They are extracted by electrolysis of the molten compound, which needs large amounts of electricity and is therefore expensive.
3Middle metals
- Middle metals Metals below carbon, such as zinc and iron, can have oxygen removed by heating with carbon or carbon monoxide.
4Least reactive
- Least reactive Copper, silver and gold are found as the element, though some copper must be reduced from its ore with carbon or hydrogen.
Section 3 of 6Extraction methods summarised
| Group of metals | Examples | Method |
|---|---|---|
| Most reactive | Potassium, sodium, lithium, calcium, magnesium, aluminium | Electrolysis of the molten chloride or oxide; costly because of the electricity needed. |
| Medium reactivity | Zinc, iron | Heated with a reducing agent such as carbon or carbon monoxide. |
| Hydrogen and copper | Copper | Found as the element, or reduced from its oxide by heating with carbon or hydrogen. |
| Least reactive | Silver, gold | Found uncombined as native metals. |
Section 4 of 6Carbon and hydrogen in the series
Not metals but included
- Not metals but included Carbon and hydrogen are non-metals, but they are placed in the reactivity series because they can reduce metal oxides.
- A reducing agent removes oxygen from a less reactive metal's oxide.
The rule
- The rule If a metal is more reactive than carbon, carbon cannot displace it from its oxide, so a stronger method is needed.
- If the metal is less reactive than carbon, heating its oxide with carbon works.
Section 5 of 6Key terms
| Term | Meaning |
|---|---|
| Native metal | A metal found in the Earth as the uncombined element. |
| Reactivity series | A list of metals in order of how readily they react. |
| Reducing agent | A substance that removes oxygen from another substance. |
| Electrolysis | Decomposing a molten ionic compound with an electric current. |
| Chemical stability | Resistance to reacting with other substances. |
Section 6 of 6Exam technique
1
Saying all metals are extracted by heating with carbon — metals above carbon need electrolysis.
2
Describing gold as unreactive because it is rare; it is because it is chemically stable.
3
Forgetting that carbon is in the reactivity series even though it is not a metal.
4
Writing that electrolysis is used for unreactive metals; it is used for the most reactive ones.