Atoms, Elements and Compounds

• Define the word "element"

  An element is a substance that contains only one type of atom.
• How many different elements are there in the periodic table?

  About 100.
• What is a "compound"?

  A compound is a substance that contains two or more elements chemically combined together.
• Describe how compounds are formed and separated, and what this involves.

  • Compounds are formed from elements by chemical reactions
  • Compounds can only be separated into elements by chemical reactions