Elements, Compounds and Mixtures

• Pure substance


  Matter with a definite and constant composition, either an element or a compound
• Element


  Composed of a single kind of atom
• Compound


  Composed of two or more elements in a specific ratio
• Compounds have physical and chemical properties different from the elements that make them up
• Mixture


  Physical combination of pure substances with no definite or constant composition
• Components of a mixture retain their own physical and chemical characteristics
• Compound


  A substance made up of two or more elements chemically combined in a fixed proportion
• Chemists can't easily separate the components of a compound, they have to resort to some type of chemical reaction
• Mixture


  A physical combination of pure substances that have no definite or constant composition
• Types of mixtures


  • Homogeneous
  • Heterogeneous
• Homogeneous mixture


  A relatively uniform mixture where every portion is like every other portion
• Heterogeneous mixture


  A mixture where the composition varies from position to position within the sample