Metals and Non-Metals: Why Materials Behave the Way They Do

Look around you.
Buildings, vehicles, wires, utensils, mobile phones, machines – all exist because of metals.
Food, air, water, medicines, fuels – all depend heavily on non-metals.
This chapter explains:

• What metals and non-metals are
• Why their properties are different
• How they react chemically
• Where metals are found
• How metals are extracted
• Why metals corrode

Understanding this chapter helps in chemistry, physics, environment studies, and everyday reasoning.

Metals and Their Physical Properties

A metal is an element that readily loses electrons to form positive ions.
Metals usually show similar physical properties because of the way their atoms are arranged and bonded.

Physical Properties of Metals

Most metals show the following properties:

1. Lustre
   Metals have a shiny surface.
This is due to reflection of light by free electrons on the surface.
   Examples: Gold, silver, copper.
   
2. Hardness
   Most metals are hard.
However, sodium and potassium are soft and can be cut with a knife.
   
3. Malleability
   Metals can be beaten into thin sheets without breaking.
   Example: Gold can be beaten into very thin gold leaf.
   
4. Ductility
   Metals can be drawn into thin wires.
   Example: Copper wires used in electrical wiring.
   
5. Conductivity
   Metals are good conductors of heat and electricity due to free electrons.
   Silver is the best conductor, but copper is used because it is cheaper.
   
6. Sonority
   Metals produce a ringing sound when struck.
   This property is used to identify metals.

Exceptions to Physical Properties

• Mercury is a metal but is liquid at room temperature
• Zinc is brittle at room temperature
• Lead is soft but not ductile

These exceptions are frequently asked in exams.

Chemical Properties of Metals

Metals are reactive substances.
Their chemical behaviour depends on how easily they lose electrons.

Reaction of Metals with Oxygen

Metals react with oxygen to form metal oxides.

2Mg + O₂ → 2MgO

Metal oxides are generally basic in nature.

Reaction of Metals with Water

Some metals react with water to form metal hydroxide and hydrogen gas.
Example:

2Na + 2H₂O → 2NaOH + H₂

Not all metals react with water.
Reactivity depends on the metal’s position in the reactivity series.

Reaction of Metals with Acids

Metals above hydrogen in the reactivity series react with dilute acids to produce salt and hydrogen gas.

Zn + 2HCl → ZnCl₂ + H₂

Copper, silver, and gold do not react with dilute acids.

Reaction of Metals with Solutions of Other Metals

A more reactive metal displaces a less reactive metal from its compound.

Zn + CuSO₄ → ZnSO₄ + Cu

This reaction forms the basis of the reactivity series.

Non-Metals and Their Physical Properties

A non-metal is an element that tends to gain electrons to form negative ions.
Non-metals generally show properties opposite to metals.

Physical Properties of Non-Metals

Most non-metals show the following properties:

• Dull appearance
• Brittle in solid form
• Poor conductors of heat and electricity
• Not sonorous

Examples:

• Sulphur
• Phosphorus
• Oxygen

Exceptions in Non-Metals

• Graphite conducts electricity
• Diamond is extremely hard
• Bromine is liquid at room temperature

These exceptions are high-frequency exam questions.

Chemical Properties of Non-Metals

Non-metals show chemical behaviour by gaining or sharing electrons.

Reaction of Non-Metals with Oxygen

Non-metals react with oxygen to form non-metal oxides.

C + O₂ → CO₂

Non-metal oxides are generally acidic in nature.

Reaction of Non-Metals with Water

Most non-metals do not react with water.
This property makes them safer to store.

Reaction of Non-Metals with Acids

Non-metals do not react with acids to produce hydrogen gas.
This is a key difference between metals and non-metals.

Occurrence of Metals – Part 1

Metals are found in nature in two forms:

• Free state
• Combined state

Metals Found in Free State

Less reactive metals occur in free state.
Examples:

• Gold
• Silver
• Platinum

These metals do not react easily with air or moisture.

Metals Found in Combined State

Highly reactive metals are found combined with other elements.
Examples:

• Sodium (as NaCl)
• Aluminium (as bauxite)

These compounds are called ores.

Metallurgy – Part 2

Metallurgy is the process of extracting metals from their ores.

Steps in Metallurgy

1. Concentration of ore
2. Roasting or calcination
3. Reduction of ore
4. Refining of metal
   Each step depends on the nature of the metal and ore.

Roasting and Calcination

• Roasting: Heating ore in presence of oxygen
• Calcination: Heating ore in absence of oxygen

Both remove impurities and convert ores into oxides.

Reduction

Metal oxides are reduced to obtain pure metals.
Different reduction methods include:

• Using carbon
• Using aluminium (thermite process)
• Electrolysis

Corrosion of Metals

Corrosion is the gradual destruction of metals due to chemical reactions with the environment.
Rusting of iron is the most common example.

Rusting of Iron

Rusting requires:

• Oxygen
• Moisture

4Fe + 3O₂ + xH₂O → 2Fe₂O₃·xH₂O

Rust weakens the metal and causes economic loss.

Prevention of Corrosion

Corrosion can be prevented by:

• Painting
• Oiling or greasing
• Galvanisation
• Alloying

FAQs – METALS & NON-METALS (Exam-Focused)

Last-Moment Notes (Cheat Sheet)

METALS & NON-METALS

Metals

• Metals lose electrons and form positive ions
• Generally lustrous, hard, malleable, ductile
• Good conductors of heat and electricity
• Exceptions: Mercury (liquid), sodium (soft)
• Metals react with oxygen to form basic oxides
• Metals above hydrogen react with acids to release H₂ gas
• More reactive metal displaces less reactive metal from solution

Non-Metals

• Non-metals gain electrons and form negative ions
• Generally dull, brittle, non-conductors
• Exceptions: Graphite conducts electricity, diamond is very hard
• Non-metals form acidic oxides
• Non-metals do not produce hydrogen with acids

Occurrence of Metals

• Free state: Gold, silver, platinum
• Combined state: Sodium, aluminium, iron
• Combined metals occur as ores

Metallurgy

• Metallurgy = extraction of metals from ores
• Steps: concentration → roasting/calcination → reduction → refining
• Roasting: heating in presence of air
• Calcination: heating in absence of air

Corrosion

• Corrosion = slow destruction of metal
• Rusting needs oxygen + moisture
• Rust weakens metal
• Prevented by painting, galvanisation, alloying

High-Frequency Exam Traps

• All metals are not hard
• All shiny substances are not metals
• All oxides are not acidic
• Corrosion is chemical, not physical
• Reactivity depends on electron loss, not hardness