year 9

• States of matter


  • Solid
  • Liquid
  • Gas
• Heating methods

  • Heating can occur by conduction, radiation, or convection
• Liquids


  • Particles are not held in fixed positions, arranged randomly, can move from place to place, and vibrate
  • Liquids do not have a fixed shape, can flow, and cannot usually be compressed
• Energy transfer


  • Energy can transfer by heating from a hotter region to a cooler region
  • Energy is transferred or transmitted from place to place
• Changes of state

  1. Substances can change states by transferring energy, heating curves and cooling curves can determine the temperature at which a state change takes place

  2. Four main changes of state: melting, freezing, evaporating, condensing
• Conduction

  • Metals are good conductors, energy transmitted by making ions vibrate faster and collide with neighbouring ions more frequently
• Solids


  • Particles are held in fixed positions in a regular arrangement, close together and vibrate about fixed positions
  • Solids have a fixed shape, cannot flow like liquids or gases, and cannot usually be compressed
• When energy transfers by heating

  • The temperature of the hotter region decreases
  • The temperature of the cooler region increases
• Temperature

  • How hot a substance is, commonly measured in degrees Celsius (°C) using a thermometer
  • Depends on the average speed of the particles in a substance
• Gases


  • Particles have enough energy to overcome attractive forces, widely spaced, move quickly in random directions, do not vibrate, and can expand to fill their container and flow
  • Gases can be compressed easily because there is lots of space between the particles
• Energy transmission


  Energy is transmitted by conduction, convection, or radiation
• Conductors

  • Base of a pan
  • Copper in the wires from a plug
  • Steel of a bell
• Atoms are the building blocks of everything
• Energy transfer in a metal rod when put into a fire

  1. Ions in the rod vibrate faster due to energy from the flame

  2. This increased vibration leads to more frequent collisions with neighbouring ions

  3. Energy is passed on through the metal by these collisions, increasing the rate of transfer
• Metal seat at a railway station


  Feels cold as it conducts energy away from the passenger’s body
• A pure substance made from only one type of atom is called an element
• Elements can combine to make compounds
• Particles can be atoms, molecules, or ions
• Even the most powerful microscopes cannot visualize a single atom
• In science, the word particle can be used in many ways
• Everything in the universe contains the atoms of one or more elements
• Everything is made of atoms
• There are 118 different elements
• Molecules are made when two or more atoms chemically bond together
• The periodic table is arranged in rows called periods and columns called groups
• Helium atoms are single atoms
• Water is made of molecules with two hydrogen atoms chemically bonded to one oxygen atom (H₂O)
• Elements are represented by letters from the alphabet, known as symbols
• The periodic table shows the chemical symbols for all the different elements
• Letters from the alphabet are used to represent chemical elements
• Every element is made up of its own type of atom
• The modern periodic table arranges elements into a unique arrangement that can be used for reference
• Each square in the table contains an element symbol of one or two letters, not the element name
• Some element symbols are simple, while others are more complex
• A zig-zag line divides metals from non-metals
• All metals are good conductors
• Insulation: The cushion on a chair is an insulator
• Cushion on a chair

  Does not allow energy to flow easily
• Atoms can form strong bonds with each other, making molecules
• Elements are listed on the periodic table