Chemistry: The Central Science

Chemistry: The Central Science

Chemistry Definition

  • Chemistry is the study of matter, its properties, and the changes it undergoes.
  • It's a fundamental science, explaining biology (living things), physics (matter and energy), and geology (study of Earth).

Chemistry as Central Science

  • Basic terminology includes atoms, molecules, and chemical reactions.
  • Macroscopic changes in matter are driven by molecular-level dynamics.

Example: Water Boiling

  • Macroscopic observation: liquid water heats, bubbles, and converts to vapor.
  • Molecular level: water molecules gain energy, speed up, and move apart to become water vapor.

Classifications of Matter

  • Matter is classified into Substances and Mixtures.
    • Substances: Pure matter with constant composition.
    • Mixtures: Two or more substances that maintain their own properties.

Substances

  • Substances have constant composition and distinct properties.
  • Substances are subdivided into Elements, Molecules, and Compounds.

Matter

  • Matter is anything that has mass and takes up space.

Elements and Molecules

  • Elements: Cannot be separated into smaller substances.
  • Molecules: Two or more atoms joined by chemical bonds; some elements exist as molecules (e.g., O2).
  • Atoms: Smallest particle of an element.

Compounds

  • Compounds are substances composed of two or more different elements joined by chemical bonds.

Mixtures

  • Mixtures
    • Heterogeneous Mixtures: Composition varies from point to point.
    • Homogeneous Mixtures: Composition is uniform throughout (also known as a solution).

Exercise: Heterogeneous or Homogeneous?

  • Examples:
    • Italian Dressing
    • Air
    • Carbonated Soda
    • Granite Stone
    • Bronze Metal
    • Salt Water

Classification of Matter Diagram

The diagram illustrates the classification of matter into substances (elements and compounds) and mixtures (homogeneous and heterogeneous).

Physical States of Matter

  • All substances exist as a solid, a liquid, or a gas.

Solids

  • Molecules are close together and arranged in an ordered fashion.
  • Molecules are held together by molecular forces and vibrate in place.
  • Solids maintain their own shape and volume.

Liquids

  • Molecules are close together, but there is no ordered arrangement.
  • Molecules can