Compounds, Molecules & MIxtures

• What are the three important terms to understand when looking at how atoms exist in the real world?

  Molecules, mixtures, and compounds
• How do molecules differ from compounds?

  • Molecules: Groups of two or more atoms held by chemical bonds
  • Compounds: Substances containing two or more different elements held by chemical bonds
• What is a molecule?


  A molecule is a group of two or more atoms held together by chemical bonds. Molecules can also contain different elements and also can just be one element that are chemically bonded together.
• What is an example of a molecule that consists of just one element?

  Oxygen
• Why is helium not considered a molecule?

  Because it exists as a single atom
• What defines a compound?

  A compound contains two or more different elements
• Why do some compounds exist as large structures rather than small molecules?

  Because they have ionic bonds
• What are mixtures and how do they differ from compounds?

  • Mixtures: Consist of two or more substances not chemically combined
  • Differences: No chemical bonds, can be separated by physical methods
• What physical methods can be used to separate mixtures?

  Filtration, crystallization, or distillation
• What happens when substances in a mixture are physically mixed together?

  They do not react with each other and have no chemical bonds
• Why can mixtures be easily separated?

  Because they consist of substances that are not chemically combined