Lecture Notes: Types of Matter

Categories of Matter

• Pure Substances

  • Defined as substances with a uniform and definite composition.
  • Can further be classified into:
    • Elements:
      • Composed of only one type of atom.
      • Examples: Oxygen gas (O₂), Helium (He), Nitrogen gas (N₂), Iron (Fe), Zinc (Zn), Elemental sulfur (S).
    • Compounds:
      • Made up of two or more different elements chemically combined.
      • Examples:
        • Water (H₂O): composed of hydrogen and oxygen.
        • Sodium chloride (NaCl): composed of sodium and chlorine.
        • Ethanol (C₂H₅OH): composed of carbon, hydrogen, and oxygen.
        • Carbon dioxide (CO₂): composed of carbon and oxygen.

• Mixtures

  • Composed of two or more pure substances mixed together.
  • Can be classified into:
    • Homogeneous Mixtures:
      • Have a uniform composition throughout.
      • Examples:
        • Salt in water: forms a clear solution.
        • Air: a mixture of gases (oxygen, nitrogen, argon, water vapor, carbon dioxide) mixed uniformly.
        • Brass: a metal alloy.
    • Heterogeneous Mixtures:
      • Do not have a uniform composition.
      • Examples:
        • Oil in water: forms distinct layers due to differences in density.
        • Sand in water: visible separation between sand and water.

Additional Resources

• For more example problems on pure substances and mixtures, check links in the description section of the video.

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These notes summarize the key topics and distinctions within the classification of matter, specifically focusing on pure substances and mixtures, along with examples and the characteristics that define each category.