chemistry

• Chemists use symbols and formulae to represent elements and compounds
• Word equations and balanced chemical equations represent the changes that happen in chemical reactions
• Atom


  The smallest part of an element that can exist
• Element


  A substance made of one type of atom only
• Atoms of each element are represented by their own chemical symbol
• Chemical symbol


  • Consists of one or two letters
  • Always starts with a capital letter, with any other letter in lower case
• Chemical symbols

  • O (oxygen)
  • Na (sodium)
• There are over 100 different elements
• The names and symbols of the elements are shown in the periodic table
• Elements are arranged into groups with similar properties
• Groups are numbered from 1 to 7, then 0
• In the periodic table, metals are on the left of the stepped line, and non-metals are on the right