C1

• Describe the arrangement and movement of particles in a solid

  • The particles are packed closely together in a regular arrangement
  • The particles vibrate in fixed positions
• Describe the arrangement and movement of particles in a liquid

  • The particles are close together but are able to move past each other
  • The particles vibrate and move around each other
• Describe the arrangement and movement of particles in a gas

  • The particles are far apart with no regular arrangement
  • The particles vibrate and move freely at high speeds
• What is atomic theory?

  The idea that everything is made up of tiny particles that can't be broken down any further and that they're separated from each other by empty space
• What did John Dalton (1800s) propose?

  He described atoms as 'solid spheres' and proposed that different types of spheres make up the different elements
• What did J.J Thomson theorise in 1897?

  • He came up with the Plum Pudding Model.
  • He deducted that atoms can't be solid spheres and must contain negatively charged particles.
  • He theorised that the atom is a general ball of positive charge with discrete electrons inside it
• What did Ernest Rutherford discover in 1909?

  • He fired alpha particles at a thin sheet of gold - some were deflected to the side and some bounced back
  • He suggested that the atom is mostly empty space, with a positively charged nucleus with negative electrons orbiting outside
• What did Niels Bohr suggest in 1913

  • That electrons orbit the nucleus in shells
• What are the limitations of the particle model?

  • It assumes all particles are small, solid and inelastic
  • It doesn't consider the intermolecular forces between particles
  • It doesn't consider the differences in atoms, molecules and ions
• What is the approximate size of an atom?

  1x10^-10 m
• What does the letter X indicate?

  The chemical symbol of an element

  
• Where are the protons in an atom?

  Locked in the nucleus
• What is the mass number?

  The number of protons and neutrons in the nucleus of an atom
• What is the atomic number?

  The number of protons in the nucleus of an atom
• Why do solids, liquids and gases expand when heated?

  When a substance is heated its molecules vibrate faster. This causes the space between the atoms to increase
• Where is the mass of an atom concentrated?

  In the nucleus
• What are the relative masses of a proton, neutron and electron?

  • Proton - 1
  • Neutron - 1
  • Electron - 0
• What are the relative charges of a proton, neutron and electron?

  • Proton - +1
  • Neutron - 0
  • Electron - -1
• What is an ion?

  An atom or molecule with a positive or negative charge
• How is an ion formed?

  When an atom gains or loses electrons.

  • Positive ions are formed when electrons are lost
  • Negative ions are formed when electrons are gained
• What are isotopes?

  Atoms of the same element with the same number of protons but a different number of neutrons