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REVIEW UNIT 3 MATERIALS

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  • What is solidifying?
    Solidifying is when a liquid changes into a solid by cooling.
  • Why can’t we see particles with our eyes?
    Because particles are too small to see.
  • What happens to the particles in a liquid when it cools down?
    The particles move slower and closer together.
  • When a liquid loses heat and becomes solid again, what is this change of state called?
    Freezing or solidifying.
  • Why do solids, liquids, and gases behave differently?
    Because their particles are arranged and move differently.
  • What do powders and liquids have in common?
    Both can be poured.
  • Why do scientists use particle models?
    To explain how substances behave using particle arrangements and movement.
  • How are particles arranged in a solid?
    Particles in a solid are packed tightly in a regular pattern.
  • Give one example of a solid, one liquid, and one gas.
    Examples: solid – wood/metal/ice; liquid – water/juice/oil; gas – air/oxygen.
  • What happens to the particles in a solid when heat is added?
    They gain energy, move faster, and move further apart.
  • Give one example of a solid that can melt.
    Examples: ice, butter, chocolate, wax.
  • What is the difference between a material and a substance?
    A material is what an object is made from; a substance is a pure material (not mixed).
  • Why must metals like gold and silver be heated to very high temperatures to melt?
    Because metals require very high temperatures to melt.
  • What happens to melted metal after it cools?
    It solidifies and becomes a solid again.
  • Give one example of a liquid that can solidify.
    Examples: water to ice, melted wax to solid wax.
  • Why do iron cans and cars sometimes turn a reddish-brown color?
    Because the iron reacts with oxygen and forms rust.
  • Why can powders like flour be poured?
    Powders are made of tiny grains with spaces between them, allowing them to flow.
  • Is the change of state a physical or chemical process? Explain briefly.
    Physical process; the substance stays the same, only the state changes.
  • What happens to water particles when they are cooled?
    They move slower and become more tightly packed (solidify).
  • What is matter made of?
    Matter is made of particles.
  • What is the name of the process when substances react and form a new substance?
    A chemical reaction.
  • How are particles arranged in a liquid?
    Particles in a liquid are close together but not in a fixed pattern.
  • Is change of state a physical or chemical process?
    It is a physical process.
  • Why can liquids change shape easily?
    Because the particles can slide past each other.
  • Why do solids melt when they gain enough energy?
    Because the particles gain enough energy to move away from each other.
  • Why do solids keep their shape?
    Because the particles are tightly packed and cannot move freely.
  • Give one example of a chemical reaction.
    Examples: burning wood, mixing cement powder with water, rusting of metal.
  • What happens to the particles of a solid when it is heated?
    They gain energy and move faster; the solid may melt.
  • What is melting?
    Melting is when a solid changes into a liquid by heating.
  • When heating ice, what state changes take place?
    Solid (ice) → liquid (water).
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