Matter and Energy

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1. Matter: Mass and Volume

Matter is everything that has mass and occupies a volume.

  • Mass: is the amount of matter a body has. It is measured with scales and balances and expressed in kilograms (kg) or grams (g).
  • Volume: is the space occupied by a body. It is measured with graduated containers and expressed in litres (L).
2. States of Matter

Matter can be presented in three different states: solid, liquid, or gas. Matter can change state if we increase or decrease its temperature.

  • Fusion/Melting: matter passes from a solid state to a liquid state.
  • Evaporation: matter passes from a liquid state to a gaseous state.
  • Condensation: matter passes from a gaseous state to a liquid state.
  • Solidification/Freezing: matter passes from a liquid state to a solid state.
3. Origin of Materials

We can classify materials according to their origin:

Natural materials: We obtain natural materials from nature. They can be:

  • Animal origin: wool, leather, silk.
  • Vegetable origin: cotton, wood, cork.
  • Mineral origin: iron, granite, copper.

Artificial materials: are created by human beings; they do not exist in nature.

Examples: petroleum → plastic, wood → paper, sand → glass.

4. Specific Properties of Materials

We choose different materials to manufacture objects according to their characteristics.

  • Resistance: if it is hard to break: concrete, rock, steel.
  • Plasticity: if when deformed, it maintains the new shape: modelling clay, clay.
  • Elasticity: if when deformed, it recovers its previous shape: elastic band, rubber.
  • Solubility: if it dissolves in water: sugar, salt.
  • Conductivity: if it lets electricity pass (conductor: copper, iron), or does not let it pass (insulator: rubber, plastic, wood).
  • Flotability/Buoyancy: if it floats in a liquid: wood, cork.
  • Behaviour towards light: transparent (glass), opaque (wood) or translucent (shower screen).
Mnemonic rule: Raúl Prepara El Solomillo Con Fuego Caliente
5. Pure Substances and Mixtures

Substances or materials can be presented in two forms:

  • Pure substances: are composed of a single component: wood, water.
  • Mixtures: are composed of more than one component.

Types of mixtures:

  • Homogeneous mixtures: the components are not distinguished: milkshake, water with salt.
  • Heterogeneous mixtures: the components are distinguished: salad, water and oil.
6. Physical and Chemical Changes

Matter can experience changes. These changes can be physical or chemical.

Physical changes: the matter does not change, only its appearance changes.

  • Deformation: stretching an elastic band.
  • Breakage: tearing a paper into pieces.
  • State changes: chocolate passes from a solid state to a liquid state.

Chemical changes: a new type of matter appears.

  • Oxidation: iron transforms into oxide (rust).
  • Combustion: paper transforms into ashes.
  • Fermentation: microorganisms transform food: milk into yoghurt or cheese.
7. Energy and its Forms

Energy is the capacity to produce changes in matter. It presents itself in different forms:

  • Mechanical energy: is the energy that all moving objects have.
  • Thermal energy: is everything that gives off heat.
  • Chemical energy: is contained in food, batteries, and fuels.
  • Electrical energy: is everything that has electricity.
  • Luminous/Light energy: is everything that emits light.
  • Nuclear energy: is contained in materials like plutonium and uranium.
Mnemonic rule: Mum Has Cheese In The Fridge

Energy can be transformed. For example, electrical energy can be converted into mechanical (fan), thermal (heater) or luminous (light bulb).

8. Sources of Energy

Sources are the natural resources from which we obtain energy.

Renewable: they do not run out with use and hardly pollute.

  • Wind power: obtained from the wind using wind turbines.
  • Hydroelectric: obtained from water in hydroelectric power stations.
  • Solar: obtained from the sun using solar panels.
  • Biomass: obtained by burning plant remains from forests and crops.

Non-renewable: they do run out with use and pollute a lot.

  • Fossil fuels: coal, petroleum, and natural gas.
  • Nuclear materials: uranium and plutonium.
9. Responsible Consumption

We must take care of our planet by making responsible use of energy:

  • Switch off lights and electrical devices that you are not using.
  • Use public transport whenever possible (bus, train, metro, etc.).
  • Recycle, reuse, and reduce consumption.

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