Chemistry Overview Lecture

What is Matter?

• Matter: Anything that occupies space and has weight.
  • States of matter:
    • Solids
    • Liquids (e.g., water)
    • Gas (e.g., vapor or steam)

What is Energy?

• Energy: Has no mass or weight; measured by its effects on matter.
  • Kinetic Energy: Performing work (e.g., muscle contraction).
  • Potential Energy: Stored energy (e.g., batteries, body fat).
  • Forms of Energy in the Body:
    • Chemical Energy: Stored in molecules, released by breaking bonds (e.g., ATP).
    • Electrical Energy: Movement of charged particles (ions, electrolytes).
    • Mechanical Energy: Muscle contraction.
    • Radiant Energy: Light energy (e.g., visible light, X-ray).

Atoms and Elements

• All matter is comprised of elements.
• Atoms: Smallest unit of an element.
  • Structure of an atom:
    • Nucleus containing protons (positively charged) and neutrons (no charge).
    • Electrons (negatively charged) orbit the nucleus.
  • Chemical Reactions:
    • Atoms form molecules by combining chemically.
    • Chemical bonds form when electrons in the outer shell interact.

Chemical Bonds

• Ionic Bonds:
  • Electrons are transferred, creating charged atoms (salts, electrolytes).
• Covalent Bonds:
  • Electrons are shared between atoms.
  • Types:
    • Single, double, triple bonds (depending on number of electrons shared).
    • Polar vs. Non-polar:
      • Non-polar: Equal sharing (e.g., CO2).
      • Polar: Unequal sharing (e.g., water), leading to hydrogen bonds.

Chemical Reactions

• Decomposition (Catabolic) Reaction:
  • Breakdown of molecules, releasing energy (e.g., digestion).
• Synthesis (Anabolic) Reaction:
  • Construction of molecules, uses energy (e.g., growth, tissue repair).
• Exchange Reaction:
  • Molecular switch of atoms.

Factors Influencing Chemical Reactions

• Temperature: Higher temperature increases reaction rate.
• Concentration: Higher concentration increases interaction chance.
• Particle Size: Smaller particles move faster, increasing interaction.
• Enzymes (Biological Catalysts): Speed up chemical reactions.