C1: Atomic Structure & The Periodic Table

• What are all substances made of?

  Atoms
• What is an atom?

  An atom is the smallest part of an element that can exist.
• How are atoms of each element represented?


  By a chemical symbol
• What does the symbol 'O' represent?

  An atom of oxygen
• What does the symbol 'Na' represent?

  An atom of sodium
• How many different elements are there approximately?

  About 100
• Where are elements shown?

  In the periodic table
• How are compounds formed?

  From elements by chemical reactions
• What do chemical reactions always involve?

  The formation of one or more new substances
• What often accompanies chemical reactions?

  A detectable energy change
• What do compounds contain?

  Two or more elements chemically combined in fixed proportions
• How can compounds be represented?

  By formulae using the symbols of the atoms from which they were formed
• How can compounds be separated into elements?

  By chemical reactions
• How can chemical reactions be represented?

  By word equations or equations using symbols and formulae