Elements,Compounds and mixtures

• What is an atom? An atom is the basic unit of matter that consists of a nucleus containing protons and neutrons, surrounded by electrons.
• What is a compound ?

  A compound is a substance made up of two or more different elements chemically bonded together.
• What is meant by fixed proportions ?


  Fixed proportions refer to a production process where inputs are used in a specific ratio and cannot be varied.
• What is a mixture?

  A combination of two or more substances that are not chemically bonded.
• What can you do if you want to separate a mixture with out using a chemical reaction ?

  you can use a physical separation technique
• What are examples of a physical separation technique?


  filtration,distillation and crystallisation or chromatography
• What is a molecule ?

  A group of atoms chemically bonded together.
• What is an example of an atom?


  Oxygen,O2
• What is an example of a compound ?


  Water,H2O