Materials

1. Basic Classification

The first thing to say: materials are usually split into two big families.

• Metals (kovy) – usually strong, hard, good conductors of heat and electricity. Most can be melted and reshaped.
• Non-metals (nekovy) – includes plastics, ceramics, glass, wood, rubber and composites. Usually lighter and often used as insulators.

2. Metals (Two main groups)

• Ferrous metals (železné kovy) – contain iron (Fe). Examples: steel (iron + carbon), cast iron, stainless steel (steel + chromium, doesn't rust).

  • Property: strong but heavy, and most of them corrode / rust when exposed to moisture.

• Non-ferrous metals (neželezné kovy) – do not contain iron. Examples: copper, aluminium, brass, bronze, gold, silver, zinc, tin.

  • Property: usually lighter, don't rust, often better conductors.

• IT connection: Copper is used for wires and PCB tracks because of excellent conductivity. Gold is used to plate connectors (CPU pins, RAM contacts) because it doesn't oxidise. Aluminium is used for heat sinks and laptop chassis because it's light and conducts heat well.

3. Non-metals

• Plastics / Polymers: Lightweight, cheap, easy to mould, good electrical insulators. Used for cable insulation, computer cases, keyboards.
  • Thermoplastics can be melted and reshaped many times (e.g. PVC, PET, ABS — ABS is the typical computer-case plastic).
  • Thermosets harden permanently and can't be remelted (e.g. epoxy resin used in PCBs).
• Ceramics: Hard, brittle, heat-resistant, electrical insulators. Used in CPU substrates, capacitors, and spark plugs.
• Glass: Transparent, brittle. Used in screens, optical fibres for fast internet.
• Composites: A combination of two or more materials (e.g. carbon fibre = carbon + resin, fibreglass). Very strong but light — used in cars, planes, drones.
• Wood, rubber, leather: Traditional natural materials, still common in furniture, tyres, etc.

4. Semiconductors (The "IT" connection)

This is your strongest area — definitely mention it.

• Semiconductors: Materials that conduct electricity better than insulators but worse than metals. Their conductivity can be controlled.
• Silicon (Si): The most important semiconductor — the base of every CPU, GPU, RAM chip and microchip. That's why Silicon Valley is called Silicon Valley.
• Germanium was used in older transistors; today gallium arsenide (GaAs) is used in high-frequency and optical devices like LEDs and solar panels.

5. Material Properties (Useful vocabulary)

If you need to extend your speaking time, describe properties:

• Hardness (tvrdost) – resistance to scratching. Diamond is the hardest natural material.
• Strength (pevnost) – how much force a material can take before breaking.
• Toughness (houževnatost) – resistance to cracking under impact.
• Elasticity (pružnost) – returns to original shape after stretching.
• Plasticity (tvárnost) – can be permanently shaped without breaking.
• Ductility (taživost) – can be drawn into a wire (typical for copper, gold).
• Malleability (kujnost) – can be hammered into thin sheets.
• Conductivity (vodivost) – conducts electricity or heat well.
• Density (hustota) – mass per volume; lead is dense, aluminium is light.
• Corrosion resistance – doesn't react with oxygen/water (gold, stainless steel).
• Melting point – temperature at which a solid turns into liquid.

6. Manufacturing / Processing

Quick vocabulary in case the examiner asks how materials are worked.

• Casting (odlévání) – pouring molten metal into a mould.
• Forging (kování) – shaping by hammering.
• Welding (svařování) – joining two metal parts by melting them together.
• Machining (obrábění) – cutting, drilling, milling on a machine tool (CNC).
• 3D printing / Additive manufacturing – building up a part layer by layer from plastic, resin or metal powder.
• Injection moulding – melted plastic is injected into a mould; how plastic parts (keyboard keys, phone cases) are mass-produced.

7. Recycling and Environment

Good closing topic — easy to fill time and link to other subjects (Environment).

• Metals like aluminium and copper are 100% recyclable without losing quality. Recycling aluminium uses about 95% less energy than producing it from ore.
• Plastics are sorted by codes (PET, HDPE, PVC, etc.) but many types are hard to recycle.
• E-waste (elektroodpad) is a growing problem — old phones and laptops contain valuable metals (gold, copper, rare earths) but also toxic materials (lead, mercury).

How to use this at the exam:

This topic links easily to almost every technical theme. Start with the basic split (metals vs non-metals), then jump to your strong area: "In my specialisation, the most important material is silicon, because..." From there you can talk about copper wires, aluminium heat sinks, ABS plastic cases — and finish with recycling and e-waste to connect it to the environment topic.