YRS : Metals and Non-metals - Notes

🌟 METALS AND NON-METALS — FULL NOTES

Class 8–10 | CBSE / DAV | Complete Chapter Notes

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1. What are Metals?

Metals are elements that generally have properties such as lustre, malleability, ductility, good electrical and thermal conductivity, and the ability to form positive ions.

Examples

• Iron (Fe)
• Copper (Cu)
• Aluminium (Al)
• Zinc (Zn)
• Silver (Ag)
• Gold (Au)
• Sodium (Na)
• Calcium (Ca)

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2. What are Non-Metals?

Non-metals are elements that generally do not show the typical properties of metals.

Examples

• Oxygen (O)
• Nitrogen (N)
• Carbon (C)
• Sulphur (S)
• Phosphorus (P)
• Chlorine (Cl)
• Bromine (Br)
• Iodine (I)

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3. Physical Properties of Metals

① Lustrous

Most metals have a shiny surface when freshly cut or polished.

Example: Gold, silver and aluminium.

② Malleable

Metals can be beaten into thin sheets.

$$\boxed{{\displaystyle \text{Malleability = ability to form thin sheets}}}$$

Example: Aluminium foil.

③ Ductile

Metals can be drawn into thin wires.

$$\boxed{{\displaystyle \text{Ductility = ability to form wires}}}$$

Example: Copper wires.

④ Good Conductors

Most metals conduct heat and electricity well.

Examples: Copper and aluminium.

⑤ Sonorous

Metals generally produce a ringing sound when struck.

⑥ Generally Hard

Many metals are hard, although there are exceptions such as sodium and potassium, which are soft and can be cut with a knife.

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4. Physical Properties of Non-Metals

Non-metals generally:

• Are dull
• Are brittle when solid
• Are poor conductors of heat and electricity
• Are not malleable
• Are not ductile
• Are not sonorous

Important Exceptions

Graphite, a form of carbon, conducts electricity.

Iodine is a lustrous non-metal.

Bromine is a liquid non-metal at room temperature.

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5. Metals vs Non-Metals

Property	Metals	Non-metals
Lustre	Generally lustrous	Generally dull
Malleability	Generally malleable	Generally brittle
Ductility	Generally ductile	Generally non-ductile
Conductivity	Good conductors	Generally poor conductors
Sonority	Generally sonorous	Generally non-sonorous
State	Mostly solids	Solids, liquids or gases
Ions	Usually form cations	Usually form anions

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6. Chemical Properties of Metals

Reaction with Oxygen

Metals react with oxygen to form metal oxides.

Example

$$2Mg+O_2\to 2MgO$$

Magnesium + Oxygen → Magnesium oxide

Most metal oxides are basic.

Some metal oxides are amphoteric, meaning they can react with both acids and bases.

Examples:

• Aluminium oxide $A{l}_2{O}_3$
• Zinc oxide $ZnO$

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7. Reaction of Non-Metals with Oxygen

Non-metals generally form non-metal oxides.

Examples:

$$C+O_2\to C{O}_2$$$$S+O_2\to S{O}_2$$

Many non-metal oxides are acidic.

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8. Reaction of Metals with Water

Different metals react with water differently.

Sodium

Sodium reacts vigorously with water:

$$2Na+2H_{2}O\to 2NaOH+H_2$$

It produces sodium hydroxide and hydrogen.

Calcium

$$Ca+2H_{2}O\to Ca(OH{)}_2+H_2$$

Iron

Iron reacts slowly with water but reacts with steam:

$$3Fe+4H_{2}O\to F{e}_3{O}_4+4H_2$$

Copper

Copper does not react readily with water.

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9. Reaction of Metals with Acids

Many metals react with dilute acids to produce a salt and hydrogen gas.

Example:

$$Zn+2HCl\to ZnC{l}_2+H_2$$

Zinc + Hydrochloric acid → Zinc chloride + Hydrogen

Test for Hydrogen

Hydrogen gas burns with a characteristic 'pop' sound when a burning splint is brought near it.

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10. Metals with Bases

Some metals such as aluminium and zinc react with strong bases.

For example, aluminium reacts with sodium hydroxide solution and produces hydrogen.

This is related to the amphoteric nature of aluminium oxide and zinc oxide.

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11. Reaction of Non-Metals with Acids

Generally, non-metals do not react with dilute acids in the same way that many metals do.

They usually do not displace hydrogen from dilute acids.

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12. Displacement Reaction

A more reactive metal can displace a less reactive metal from its salt solution.

Example

Iron + Copper sulphate:

$$Fe+CuS{O}_4\to FeS{O}_4+Cu$$

Iron is more reactive than copper.

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Observation

• Blue $CuS{O}_4$ solution becomes greenish due to $FeS{O}_4$.
• Copper is deposited on the iron nail.

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13. Reactivity Series

The reactivity series arranges metals from more reactive to less reactive.

$$\boxed{{\displaystyle K>Na>Ca>Mg>Al>Zn>Fe>Sn>Pb>H>Cu>Hg>Ag>Au}}$$

A common mnemonic is:

Please Stop Calling Me A Zebra, I Like Her Calling Me A Smart Girl

The exact mnemonic can vary; focus on learning the order.

Important

• Potassium and sodium are highly reactive.
• Gold and platinum are very unreactive.
• Hydrogen is included for comparison even though it is not a metal.

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14. Extraction of Metals

Metals are generally obtained from their ores.

Mineral

A naturally occurring substance containing a metal or its compounds.

Ore

A mineral from which a metal can be extracted economically and conveniently.

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15. Steps in Extraction

The general process includes:

Ore → Concentration → Conversion to suitable compound → Reduction → Refining

The exact process depends on the metal and its reactivity.

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16. Metals of Different Reactivity

Highly Reactive Metals

Examples:

• K
• Na
• Ca
• Mg
• Al

They are generally extracted using electrolytic methods.

Moderately Reactive Metals

Examples:

• Zn
• Fe
• Pb

Their compounds can often be reduced using carbon or carbon monoxide after suitable processing.

Low Reactive Metals

Examples:

• Cu
• Ag
• Au

Some occur in native form or can be obtained by relatively easier reduction/refining processes.

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17. Ionic Compounds

When a metal transfers electrons to a non-metal, oppositely charged ions are formed.

Example: Sodium Chloride

Sodium:

$$Na\to N{a}^{+}+e^{-}$$

Chlorine:

$$Cl+e^{-}\to C{l}^{-}$$

Then:

$$N{a}^{+}+C{l}^{-}\to NaCl$$

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18. Properties of Ionic Compounds

Ionic compounds generally:

1. Are hard and brittle

They have strong electrostatic forces between ions.

2. Have high melting and boiling points

A large amount of energy is needed to separate the ions.

3. Conduct electricity in molten state

When molten, ions are free to move.

4. Conduct electricity in aqueous solution

Ions can move through the solution.

5. Usually do not conduct electricity in solid state

The ions are fixed in their positions.

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19. Corrosion

The slow deterioration of a metal due to chemical reactions with substances in the environment is called corrosion.

Example: Rusting of Iron

Iron reacts with oxygen and moisture to form rust.

Rust is mainly hydrated iron(III) oxide.

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20. Conditions Required for Rusting

Rusting requires:

$$\boxed{{\displaystyle \text{Iron + Oxygen + Water/Moisture}}}$$

Removing either oxygen or moisture can prevent or reduce rusting.

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21. Prevention of Corrosion

Painting

Paint prevents contact with air and moisture.

Oiling/Greasing

Oil or grease forms a protective layer.

Galvanisation

Iron or steel is coated with zinc.

Alloying

Mixing metals with other elements can improve resistance to corrosion.

Electroplating

A thin protective metal layer is deposited on another material.

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22. Alloys

An alloy is a homogeneous mixture of two or more metals, or of a metal and a non-metal, designed to have useful properties.

Examples

Alloy	Main constituents
Brass	Copper + Zinc
Bronze	Copper + Tin
Solder	Lead + Tin in traditional formulations
Stainless steel	Iron + Chromium + Nickel + Carbon
Steel	Iron + Carbon

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23. Why Are Alloys Used?

Alloys may have:

• Greater strength
• Greater hardness
• Better corrosion resistance
• Better appearance
• Special electrical or mechanical properties

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24. Uses of Metals

Iron

Used in:

• Buildings
• Bridges
• Machines
• Vehicles
• Tools

Copper

Used in:

• Electrical wires
• Motors
• Electrical equipment

Aluminium

Used in:

• Aircraft
• Utensils
• Packaging
• Electrical transmission

Gold and Silver

Used in:

• Jewellery
• Decorative articles
• Electronics

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25. Uses of Non-Metals

Oxygen

Required for respiration and supports combustion.

Nitrogen

Used in fertilizers and many industrial processes.

Chlorine

Used for water disinfection and manufacture of chemicals.

Iodine

Used in antiseptic preparations and nutrition in appropriate forms.

Carbon

Used in fuels, electrodes and many industrial materials.

Sulphur

Used in manufacture of sulphuric acid, fertilizers and other chemicals.

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⭐ 26. Important Exceptions

Remember these for exams:

• Mercury → liquid metal at room temperature.
• Bromine → liquid non-metal at room temperature.
• Sodium and potassium → soft metals.
• Graphite → non-metal that conducts electricity.
• Iodine → lustrous non-metal.
• Gallium → metal with a very low melting point.
• Aluminium oxide and zinc oxide → amphoteric oxides.

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27. Metal Oxides — Acidic, Basic and Amphoteric

Basic Oxides

Most metal oxides are basic.

Example:

$$MgO$$

Acidic Oxides

Many non-metal oxides are acidic.

Examples:

$$C{O}_2,S{O}_2$$

Amphoteric Oxides

React with both acids and bases.

Examples:

$$A{l}_2{O}_3,ZnO$$

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28. Metals and Non-Metals in the Periodic Table

Generally:

Metals → left and centre

Non-metals → upper right

Metalloids → along the zig-zag boundary

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29. Metalloids

Elements that show properties intermediate between metals and non-metals are called metalloids.

Examples:

• Boron
• Silicon
• Germanium
• Arsenic
• Antimony
• Tellurium

Silicon is particularly important as a semiconductor.

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30. Electronic Nature of Metals

Metals generally have a tendency to lose electrons.

For example:

$$Na\to N{a}^{+}+e^{-}$$

Thus metals generally form positive ions (cations).

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31. Electronic Nature of Non-Metals

Non-metals generally tend to gain electrons or share electrons.

Example:

$$Cl+e^{-}\to C{l}^{-}$$

Thus many non-metals form negative ions (anions) when they gain electrons.

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32. Why Metals Conduct Electricity

Metals contain mobile electrons that can move through the structure, allowing electric current to flow.

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33. Why Ionic Compounds Conduct Electricity When Molten

In solid ionic compounds, ions are fixed.

In molten or aqueous states, ions become mobile and can carry electric charge.

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34. Why Ionic Compounds are Brittle

When layers of ions shift, similarly charged ions can come close together. Their repulsion can cause the crystal to split.

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35. Metal + Oxygen

General reaction:

$$\boxed{{\displaystyle \text{Metal}+\text{Oxygen}\to \text{Metal oxide}}}$$

Example:

$$2Mg+O_2\to 2MgO$$

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36. Metal + Water

General examples:

$$2Na+2H_{2}O\to 2NaOH+H_2$$$$Ca+2H_{2}O\to Ca(OH{)}_2+H_2$$

Different metals show very different rates of reaction with water.

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37. Metal + Acid

General reaction:

$$\boxed{{\displaystyle \text{Metal}+\text{Acid}\to \text{Salt}+\text{Hydrogen}}}$$

Example:

$$Zn+2HCl\to ZnC{l}_2+H_2$$

This applies to metals that are sufficiently above hydrogen in the activity series and under suitable conditions.

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38. Displacement Reaction — Key Rule

A more reactive metal displaces a less reactive metal from its salt solution.

Example:

$$Zn+CuS{O}_4\to ZnS{O}_4+Cu$$

Because:

$$Zn>Cu$$

in the reactivity series.

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39. Extraction Flow Chart

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Ore

↓

Concentration

↓

Conversion to oxide/other suitable compound

↓

Reduction

↓

Refining

↓

Pure metal

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40. Thermite Reaction

Aluminium can reduce certain metal oxides because aluminium has a high affinity for oxygen.

Example:

$$F{e}_2{O}_3+2Al\to A{l}_2{O}_3+2Fe+\text{heat}$$

This is called the thermite reaction.

Uses

It has been used for joining/repairing railway tracks and other heavy iron/steel components.

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41. Electrolytic Refining

Electrolytic refining is used to obtain highly pure metals.

It is commonly used for metals such as:

• Copper
• Zinc
• Nickel
• Silver

In copper refining:

Anode → impure copper

Cathode → pure copper

Electrolyte → copper sulphate solution

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42. Reactivity and Displacement

Suppose:

$$Fe+CuS{O}_4\to FeS{O}_4+Cu$$

This reaction occurs because:

$$Fe>Cu$$

But:

$$Cu+FeS{O}_4\to \text{No reaction}$$

because:

$$Cu<Fe$$

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43. Activity Series — Easy Revision

$$\boxed{{\displaystyle K>Na>Ca>Mg>Al>Zn>Fe>Sn>Pb>H>Cu>Hg>Ag>Au}}$$

Top

More reactive.

Bottom

Less reactive.

Important

A metal above hydrogen can generally displace hydrogen from dilute non-oxidising acids, subject to reaction conditions.

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44. Minerals vs Ores

Mineral

Naturally occurring substance containing a metal or its compounds.

Ore

A mineral from which extraction of the metal is economically feasible.

Every ore is a mineral, but every mineral is not necessarily an ore.

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45. Corrosion vs Rancidity

Do not confuse these:

Corrosion → metals

Rancidity → fats and oils

Rancidity occurs when fats/oils undergo oxidation and develop unpleasant smell and taste.

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46. Prevention of Rancidity

Rancidity can be reduced by:

• Refrigeration
• Airtight containers
• Antioxidants
• Nitrogen flushing in some packaged foods
• Keeping food away from excessive heat and light

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47. Metals in the Human Body

Some metals are essential in small amounts.

Examples:

• Iron → important for haemoglobin
• Calcium → bones and teeth
• Sodium → fluid and nerve functions
• Potassium → nerve and muscle functions
• Magnesium → many biological reactions

Excess amounts of some metals can be harmful.

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🔥 48. Important Chemical Equations

Magnesium + Oxygen

$$2Mg+O_2\to 2MgO$$

Zinc + Hydrochloric Acid

$$Zn+2HCl\to ZnC{l}_2+H_2$$

Sodium + Water

$$2Na+2H_{2}O\to 2NaOH+H_2$$

Calcium + Water

$$Ca+2H_{2}O\to Ca(OH{)}_2+H_2$$

Iron + Copper Sulphate

$$Fe+CuS{O}_4\to FeS{O}_4+Cu$$

Thermite Reaction

$$F{e}_2{O}_3+2Al\to A{l}_2{O}_3+2Fe+\text{heat}$$

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⭐ 49. Important Exam Questions

Q1. What is malleability?

Answer: The ability of a metal to be beaten into thin sheets.

Q2. What is ductility?

Answer: The ability of a metal to be drawn into thin wires.

Q3. Why is copper used for electrical wiring?

Answer: Copper has high electrical conductivity and can be drawn into wires.

Q4. Why are sodium and potassium stored under oil?

Answer: They are highly reactive and can react rapidly with oxygen and moisture.

Q5. Why do ionic compounds have high melting points?

Answer: Strong electrostatic forces hold oppositely charged ions together.

Q6. Why do ionic compounds conduct electricity in molten state?

Answer: Their ions are free to move in the molten state.

Q7. What is corrosion?

Answer: The gradual deterioration of a metal due to chemical reactions with its environment.

Q8. What is galvanisation?

Answer: Coating iron or steel with zinc to protect it from corrosion.

Q9. What is an alloy?

Answer: A homogeneous mixture of two or more metals, or a metal and a non-metal.

Q10. What is the thermite reaction?

Answer: A highly exothermic reduction reaction in which aluminium reduces certain metal oxides to the metal.

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🧠 50. Very Important One-Liners

1. Metals generally form cations.
2. Non-metals generally form anions when they gain electrons.
3. Metals are generally good conductors.
4. Graphite is a conducting non-metal.
5. Mercury is a liquid metal at room temperature.
6. Bromine is a liquid non-metal at room temperature.
7. Iodine is a lustrous non-metal.
8. Sodium is a highly reactive metal.
9. Gold is a very unreactive metal.
10. $A{l}_2{O}_3$ is amphoteric.
11. $ZnO$ is amphoteric.
12. Metal + acid often gives salt + hydrogen.
13. More reactive metal displaces a less reactive metal.
14. Rusting requires iron, oxygen and moisture.
15. Galvanisation uses zinc.
16. Brass = copper + zinc.
17. Bronze = copper + tin.
18. Stainless steel contains iron, chromium and commonly nickel and carbon.
19. Power lines commonly use aluminium because of its useful combination of conductivity, low density and cost.
20. Copper is widely used for electrical wiring.

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🎯 51. Quick Comparison

Metals	Non-Metals
Usually lustrous	Usually dull
Malleable	Generally brittle if solid
Ductile	Generally non-ductile
Good conductors	Generally poor conductors
Usually sonorous	Generally non-sonorous
Usually form cations	Often form anions
Usually form basic oxides	Often form acidic oxides
Mostly solids	Solids, liquids or gases
Lose electrons easily	Gain/share electrons

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📚 52. Must-Learn Reactions

$$\boxed{{\displaystyle 2Mg+O_2\to 2MgO}}$$$$\boxed{{\displaystyle Zn+2HCl\to ZnC{l}_2+H_2}}$$$$\boxed{{\displaystyle 2Na+2H_{2}O\to 2NaOH+H_2}}$$$$\boxed{{\displaystyle Fe+CuS{O}_4\to FeS{O}_4+Cu}}$$$$\boxed{{\displaystyle F{e}_2{O}_3+2Al\to A{l}_2{O}_3+2Fe}}$$

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📝 53. Practice Questions

MCQs

1. Which is a liquid metal at room temperature?
A. Iron
B. Mercury
C. Copper
D. Aluminium

Answer: B

2. Which non-metal conducts electricity?
A. Sulphur
B. Oxygen
C. Graphite
D. Phosphorus

Answer: C

3. Which metal is used for galvanisation?
A. Copper
B. Zinc
C. Silver
D. Gold

Answer: B

4. Brass contains:
A. Cu + Zn
B. Cu + Sn
C. Fe + C
D. Al + Cu

Answer: A

5. Which oxide is amphoteric?
A. CO₂
B. SO₂
C. ZnO
D. Na₂O

Answer: C

Short Answer

6. Define corrosion.
7. Define alloy.
8. What is malleability?
9. What is ductility?
10. Why are ionic compounds brittle?
11. Explain displacement reaction with an equation.
12. What is galvanisation?
13. Why does zinc displace copper from copper sulphate?
14. Explain the formation of NaCl.
15. Write the reactivity series.

Long Answer

16. Explain the physical and chemical properties of metals.
17. Explain the physical and chemical properties of non-metals.
18. Explain extraction of metals according to their reactivity.
19. Explain corrosion and methods of preventing it.
20. Explain ionic compound formation and its properties.

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