particle model or matter

• What does the particle model of matter state about all matter?

  Everything is made up of lots of tiny particles.
• How can the behavior of matter be explained according to particle theory?

  The behavior of matter can be explained in terms of how tiny particles move and the forces between them.
• What are the characteristics of particles in different states of matter?

  • Solids: Particles vibrate about fixed positions.
  • Liquids: Weaker forces of attraction; particles move randomly at low speeds.
  • Gases: Almost no forces of attraction; particles move freely and randomly at high speeds.
• What happens to gas particles when they collide with the walls of their container?

  They exert a force on the walls, creating pressure.
• What is the formula for pressure in a gas?

  Pressure is the force exerted per unit area.
• How does increasing the temperature of a gas affect its pressure?

  Increasing the temperature increases the average kinetic energy and speed of the particles, raising the pressure.
• What is the relationship between temperature and average kinetic energy in gases?

  The higher the temperature, the higher the average kinetic energy of the particles.
• What factors increase the pressure of a gas in a sealed container when temperature is increased?

  • Particles travel quicker, hitting the walls more often.
  • Each particle has larger momentum, exerting a bigger force upon collision.
• What does density measure in a substance?

  Density measures the compactness of a substance, relating mass to volume.
• What are the units of density?

  Density is measured in kg/m³ or g/cm³.
• How is density calculated?

  Density is calculated using the formula: $p =$$\frac{m}{V}$.
• If a gold bar has a mass of 12 kg and a volume of $6.3 \times 10^{-4} \text{ m}^3$, what is its density?


  The density is $19,000 \text{ kg/m}^3$.
• How does the arrangement of particles affect the density of materials?

  • Dense materials have particles packed tightly together.
  • Less dense materials have particles that are more spread out.
• What happens to the density of a material when it is compressed?

  Compression makes the particles closer together, increasing the density.
• What are the methods to measure density for solids and liquids?

  • Solids: Measure mass, calculate volume, then use density formula.
  • Liquids: Use a measuring cylinder to measure volume and mass, then calculate density.
• How do you find the density of a gemstone that displaces 5 cm³ of water and has a mass of 0.079 kg?

  The density is $\frac{0.079 \text{ kg}}{5 \text{ cm}^3} =$$0.0158 \text{ kg/cm}^3 =$$15.8 \text{ g/cm}^3$.
• What is internal energy in a system?

  • Total energy stored by particles in a system.
  • Includes kinetic and potential energy stores.
• What happens to the particles in a system when it is heated?

  Heating transfers energy to the particles, increasing their kinetic and potential energy stores.
• What occurs during a change of state in a substance?

  Particles gain enough energy to break the bonds holding them together.
• What are the changes of state when heating a solid or liquid?

  • Solid to Liquid: Melting
  • Liquid to Gas: Boiling or vaporizing