Metals and Non-metals · Lesson 13 of 13
Chapter Summary and Practice
“Every property, reaction and extraction method returns for one final metal-powered review.”
• Review the physical and chemical differences between metals and non-metals. • Use the reactivity series to explain reactions, extraction and displacement. • Review electron transfer and the properties of ionic compounds. • Connect minerals, ores, extraction and refining into one process chain. • Apply corrosion and alloy concepts to practical situations.
The chapter follows one continuous story. Physical properties first help us recognise metals and non-metals. Chemical reactions reveal that metals differ greatly in reactivity. The reactivity series organises those differences and also explains displacement, occurrence in nature and the extraction method required. Electron transfer explains ionic compounds, while refining and corrosion show how metals are purified and protected.
At A Glance
Physical Properties
Metals are generally lustrous, malleable, ductile, sonorous and good conductors of heat and electricity. Non-metals usually show opposite trends, but exceptions include mercury, iodine, graphite, diamond and soft alkali metals.
Chemical Reactivity
Metals react with oxygen, water, acids and salt solutions according to reactivity. Metal oxides are generally basic, while aluminium oxide and zinc oxide are amphoteric. Water reactions range from violent cold-water reactions to steam-only reactions or no reaction.
Reactivity Series
K, Na, Ca, Mg, Al, Zn, Fe, Pb, H, Cu, Hg, Ag, Au is used to predict displacement. A higher metal can displace a lower metal from its salt solution, and metals above hydrogen can displace hydrogen from suitable dilute acids.
Ionic Bonding
Metals lose electrons to form cations and non-metals gain electrons to form anions. Na⁺ and Cl⁻ form by transfer of one electron, while Mg²⁺ balances with two Cl⁻ ions. Strong electrostatic attraction holds ionic compounds together.
Properties Of Ionic Compounds
Ionic compounds are generally hard, brittle solids with high melting and boiling points. They are usually soluble in water and conduct when molten or dissolved because ions can move, but not when solid.
Occurrence And Metallurgy
Minerals occur naturally. Ores are useful minerals from which metals can be extracted profitably. Gangue is removed during enrichment. Extraction then depends on reactivity.
Extraction By Reactivity
| Reactivity Group | Typical Route |
|---|---|
| Low | Free occurrence or simple heating in suitable cases |
| Middle | Convert sulphides/carbonates to oxides, then reduce |
| High | Electrolytic reduction |
Roasting And Calcination
Roasting uses excess air for sulphides. Calcination uses limited air for carbonates.
Reduction And Thermit Reaction
The thermit reaction releases enough heat to form molten iron and can join railway tracks or repair machine parts.
Electrolytic Extraction And Refining
Highly reactive metals require electrolysis for extraction. Refining is different: impure metal is the anode, pure metal is the cathode, and a metal-salt solution is the electrolyte.
Corrosion And Prevention
Iron rusts when both air and water are present. Silver blackens and copper develops a green coating. Painting, oiling, greasing, galvanising, chrome plating, anodising and alloying can reduce corrosion.
Important Equations
Worked Problems
Problem
Will copper displace silver from silver nitrate solution?
- 1.Copper is above silver in the reactivity series.
- 2.Copper is therefore more reactive.
- 3.A more reactive metal displaces a less reactive metal from its salt solution.
- 4.A displacement reaction is expected.
Problem
A metal lies near the top of the reactivity series and cannot be reduced by carbon. Which approach is appropriate?
- 1.High position means strong affinity for oxygen.
- 2.Carbon cannot remove oxygen effectively.
- 3.Highly reactive metals are obtained by electrolytic reduction.
- 4.Electrolysis of a suitable molten compound is appropriate.
Problem
Why does molten MgCl₂ conduct but solid MgCl₂ does not?
- 1.Both contain Mg²⁺ and Cl⁻ ions.
- 2.In the solid, ions are fixed.
- 3.In the melt, ions move freely.
- 4.Mobile ions carry charge, so molten MgCl₂ conducts.
Revise, Reflect, Refine
| Common Confusion | Correction |
|---|---|
| Malleability and ductility are the same | Malleability forms sheets; ductility forms wires. |
| Every metal oxide is basic | Aluminium oxide and zinc oxide are amphoteric. |
| Every metal reacts with water | Water reactivity ranges from violent reaction to no reaction. |
| Any metal can displace any other | A higher metal displaces a lower one. |
| Solid ionic compounds should conduct | Their ions are present but fixed. |
| Roasting and calcination are interchangeable | Roasting treats sulphides in excess air; calcination treats carbonates in limited air. |
| Extraction and refining are the same | Extraction obtains metal; refining purifies it. |
The Journey Beyond
A shiny wire, a salt crystal, an ore and a rusted iron nail appear unrelated, but the same ideas of structure, electron transfer, reactivity and energy connect them.
Quiz
Which property allows metals to be drawn into wires?
Which oxide is amphoteric?
Which statement about ionic compounds is correct?
Which process converts zinc sulphide to zinc oxide using excess air?
What is the correct arrangement in electrolytic refining?
Practice Problems
- Differentiate metals and non-metals using physical properties and list at least three exceptions.
- Use the reactivity series to predict whether zinc reacts with copper sulphate and whether copper reacts with zinc sulphate.
- Explain formation of NaCl and MgCl₂ by electron transfer.
- Explain why ionic compounds have high melting points and why they conduct only when ions are mobile.
- Define mineral, ore and gangue, then explain why enrichment is needed.
- Differentiate roasting and calcination with equations.
- Explain why high-reactivity metals need electrolysis while many middle-reactivity metal oxides can be reduced.
- Write and explain the thermit reaction.
- Describe electrolytic refining of copper, including anode mud.
- Explain the conditions necessary for rusting and give four methods of corrosion prevention.
- Explain why stainless steel and solder are useful alloys.
- Give reasons why aluminium can be useful despite being reactive, using its protective oxide layer.
Key Takeaways
• Physical properties help identify metals and non-metals, but exceptions mean chemical behaviour is also essential. • The reactivity series predicts reactions with acids and salt solutions and guides extraction methods. • Ionic compounds form by electron transfer and their properties follow from strong electrostatic attraction and ion mobility. • Metallurgy includes enrichment, extraction and refining, with methods chosen according to reactivity. • Corrosion can be reduced through protective coatings, galvanisation, anodising and alloying.
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Corrosion And Prevention Of Corrosion
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