ks3 chemistry

• What are examples of substances made of different materials?

  Gold and water, wood and air
• What is a substance?

  A substance has one type of material only
• What is a mixture?

  A mixture is made of two or more substances
• What are all materials made of?


  Tiny particles
• What is true about the particles in a substance?

  All particles in a substance are the same
• What determines the properties of a substance?

  Size, shape, mass, arrangement, and separation of particles
• How does the arrangement of particles affect properties?

  It affects how they behave and interact
• What are the three states of matter?

  Solid, liquid, gas
• How can the properties of substances in different states be explained?

  • Using the particle model
  • Each state has unique particle arrangements and behaviors
• What is the particle model explanation for solids?

  Particles are touching, arranged in a pattern
• What is the particle model explanation for liquids?

  Particles are touching but can slide over each other
• What is the particle model explanation for gases?

  Particles are far apart and moving quickly
• What is density a measure of?

  The mass in a given volume
• In what units is density measured?

  kg/m³
• What factors affect the density of a substance?

  Mass, arrangement of particles, and state
• How does the density of a gas compare to that of liquids and solids?

  It is much less than liquids and solids
• How does the density of a substance in solid and liquid states compare?

  It is about the same in both states
• What is unusual about the density of water?

  It is less dense in solid state
• What are examples of changes of state?

  • Melting
  • Boiling
  • Evaporation
  • Sublimation
• What happens to particles during melting?

  They vibrate more and slide over each other
• What occurs during sublimation?

  Particles in a solid escape into gas
• What happens during boiling?

  Bubbles of gas form in the liquid
• When does evaporation occur?

  At any temperature above freezing point
• What happens to particles during freezing?

  They move slowly and form a fixed pattern
• What occurs during condensing?

  Particles move closer and slide over each other
• What is the melting point?

  The temperature where solid turns to liquid
• What is diffusion?

  Movement of particles from high to low concentration
• In which states of matter does diffusion occur?

  Liquid and gas states
• Why does diffusion happen more slowly in liquids than in gases?

  Particles are less free to move in liquids
• What happens to the rate of diffusion at higher temperatures?

  Particles move faster
• How does the state of a substance affect diffusion?

  Liquids diffuse more slowly than gases
• What effect does particle size have on diffusion rates?

  Bigger particles diffuse more slowly
• What are the key terms related to diffusion?

  • Concentration: Amount of substance in a given volume
  • Diffusion: Movement of particles from high to low concentration
• What is an element?

  A substance that cannot be broken down
• Can you name three examples of elements?

  Gold, silver, oxygen
• How many elements are there approximately?

  About 100 elements
• What is the chemical symbol for hydrogen?

  H
• Where are elements listed?

  In the Periodic Table
• What is an atom?

  The smallest part of an element
• How many types of atom are there?

  About 100 types of atom