The Chemistry of Living Things

The Chemistry of Living Things: Matter, Energy, and Life

Essential Question: Medicine vs. Poison

• The difference between medicine and poison is often nuanced.
• While both can originate from the same organism, various factors influence how a chemical impacts humans upon use.

Matter

• Definition: Anything that takes up space and has mass.
• Element: A pure substance made of only one kind of atom.
• Atom: The fundamental building block of matter; the smallest possible particle of an element.
  • Sub-atomic Particles:
    • Electron: Negatively charged.
    • Proton: Positively charged.
    • Neutron: No charge (neutral).

Energy

• Definition: The ability to do work; in biology, it drives the physical and chemical processes essential for life.
• Temperature: A measurement of the average kinetic energy of the particles within a substance.
• Role of Energy in Living Things:
  • Living organisms require access to energy to sustain life processes.
  • Nonliving things also possess energy.
  • The world would be fundamentally different without energy.
• Types of Energy:
  • Mechanical Energy (kinetic and potential).
  • Acoustic Energy (sound).
  • Light Energy.
  • Thermal Energy.
  • Electrical Energy.
  • Chemical Energy.

Changes in Matter

• Physical Change: A change in a substance that does not alter its chemical identity (e.g., a change of form or state).
  • Examples:
    • Boiling water (changes from liquid to gas, but remains $H_2O$).
    • Breaking a bone.
• Chemical Change: A change in a substance that causes it to change its chemical identity (a new substance is formed).
  • Examples:
    • Baking a cake (ingredients chemically react to form new compounds).
    • Photosynthesis ($6CO<em>2 + 6H</em>2O + ext{light energy} \rightarrow C<em>6H</em>{12}O<em>6 + 6O</em>2$).
    • Burning a candle (wax reacts with oxygen to produce carbon dioxide and water vapor, e.g., $2C<em>{18}H</em>{38}(s) + 55O<em>2(g) \rightarrow 36CO</em>2(g) + 38H_2O(g)$).
      • Observation: As a candle burns and gets smaller, the matter is not lost; it chemically changes into gaseous products like carbon dioxide and water vapor that dissipate into the environment.

Law of Conservation of Matter and Energy

• This fundamental law states that the total amount of matter and energy in the universe never changes.
• When matter or energy appears