Science EOY revision

• Elements


  • Can be classified as metals or non-metals, depending on their properties
• Common properties of metals

  • High melting point solids
  • Strong and flexible
  • Shiny (when polished)
  • Good conductors of heat
  • Good conductors of electricity
• Metals


  • copper, iron, aluminium, zinc, and tin
• Mercury


  The only liquid metal
• Common properties of non-metals

  • Low melting point (gases, liquids and solids)
  • Brittle (when solid)
  • Not shiny
  • Poor conductors of heat
  • Poor conductors of electricity
• Non-metals


  • sulfur, oxygen, nitrogen, carbon and iodine
• The uses of an element depend on its properties
• Uses of copper and aluminium

  • Electrical cables as they are strong, flexible and conduct electricity very well
• Compounds


  Formed when elements are mixed and react so that the atoms join together
• Naming compounds


  1. If there is a metal in the compound, the name of the metal goes first

  2. If the compound contains only two elements then one of the element's name has its ending changed to 'ide'

  3. If a compound contains two elements plus oxygen, then the name ending of one of the elements is changed to 'ste'
• Chemical reactions


  Always form one or more new substances
• Signs of chemical reactions

  • Colour change
  • Gas being given off
  • Solid forming in a liquid
  • Energy change
• How chemical reactions start

  1. Some just by mixing the right substances together

  2. Heat is often needed to start a reaction, but once started many reactions give out heat

  3. Others need a continuous supply of energy to keep them going
• Examples of chemical reactions

  • Burning, cooking, rusting, digesting food
• Modelling chemical reactions using word equations

  1. Reactants

  2. Products
• Thermal decomposition reactions


  Involve breaking down a single compound using heat
• Example of thermal decomposition reaction


  • Heating copper carbonate produces copper oxide and carbon dioxide
• Thermal decomposition reactions are used in industry to extract metals
• Sorting and presenting data

  The way data is sorted and presented depends on the type of variable and what you want to show
• Types of data visualisation

  • Tables
  • Bar charts
  • Line graphs
  • Scatter graphs
  • Pie charts
• Discrete data


  Only certain number values
• Example of a pie chart


  • Pie chart of gases in air
• Atoms


  Tiny particles that make up all substances
• Molecules


  Small groups of atoms bonded together
• Elements


  Simple substances made up of only one kind of atom
• There are about 90 different types of atom found on Earth, therefore there are about 90 different elements
• Compounds


  Contain more than one kind of atom (more than one element) bonded (joined) together
• Mixtures


  Contain two or more substances which are not joined together
• Periodic table


  Lists all 118 known elements
• Element symbols


  One or two letters, first letter always capital, second always lowercase
• Although there are only about 90 natural elements, there are millions of compounds
• We obtain all the elements and compounds we need for living from the Earth's atmosphere and crust
• Our resources are limited and some may run out in the near future. We need to take care of our resources, recycle more and make less waste
• Light


  Travels in straight lines from a source, as transverse waves, much faster than sound, and does not need a substance to travel through
• Transparent objects


  Allow light to pass straight through
• Opaque objects


  Block all light
• Translucent objects


  Allow some light to pass through, but it is scattered so you do not see a clear image
• Transmission and absorption


  Transparent materials let light pass straight through (transmit light), opaque surfaces can absorb or reflect light
• Reflection


  Light rays are scattered by rough surfaces (diffuse reflection), mirrors and shiny materials reflect light evenly (specular reflection)
• Law of reflection


  Angle of incidence equals angle of reflection