Science Notes on Scientific Modeling, Atomic Models, and Matter

Scientific Modeling

• Definition: Representation of real phenomenon difficult to observe directly.
• Used to explain, predict behaviors, physics, chemistry, ecology, and Earth sciences.

Types of Models

• Model: Representation of object/system.
  • Physical Models: Look like what they represent (e.g., model flower).
  • Mathematical Models: Equations and data (e.g., weather map).
  • Conceptual Models: Systems of ideas, comparisons to explain an idea (e.g., universe origin).

Model Size

• Represent very small (cells, particles) or very large (Earth, solar system) things.

Models and Scientific Knowledge

• Illustrate and explain scientific theories.
  • Theory: Unifying explanation supported by testing.
  • Theories/models can change with new observations.

Scientific Laws

• Formed when a theory and its models correctly predict experiment results.
  • Law: Summary of experimental results/observations.
  • Laws describe what happens, not why.

Model Applications

• Help understand complex systems by enabling analysis and predictions.
• Physical models are simplified representations (globe, map).
• Conceptual models connect ideas (phenomenon/event).
• Mathematical models use equations, often on computers.
• Simulation models use digital prototypes.
• Used to test ideas and predict the future.
• Accuracy assessed using past data.
• Limitations: Simpler than real systems, may not be perfectly accurate, improved with careful construction and computing power.

Atomic Models

• Democritus: Atoms are uniform, solid, hard, incompressible, indestructible.
• Dalton's Atomic Model:
  • Matter is made of indivisible atoms.
  • Atoms of the same element have the same size and mass. Atoms of different elements have different sizes and masses.
• Thomson's Atomic Model:
  • Plum pudding model: Sphere of positive charges with electrons distributed inside.
  • Atoms are electrically neutral.
• Rutherford's Atomic Model:
  • Tiny, dense, positively charged nucleus.
  • Electrons circulate around the nucleus (like planets around the sun).
• Bohr's Atomic Model:
  • Similar to Rutherford model, planetary model.
  • Electrons orbit nucleus.
• Quantum Atomic Model:
  • Atoms as matter waves.
  • Predicts 3D region around the nucleus (atomic orbital).

Atomic Theory

• Ancient philosophical speculation of combinations of small, indivisible particles/atoms.
• Modern scientific theory of matter elements consist of aggregations of similar subunits/atoms.

Particle Model of Matter

• Explains arrangement, movement, and interaction of particles.
  • Solid: Close together, regular pattern, vibrate.
  • Liquid: Close together, random, move around each other.
  • Gas: Far apart, random, move quickly in all directions.

Matter

• Anything that occupies space and has mass.
• Exists as solid, liquid, or gas.
• Made of tiny particles (atoms and molecules).

States of Matter

• Solids: Definite size, shape, and mass (compact particles).
• Liquids: Definite volume, no definite shape (particles close with spaces).
• Gas: No definite shape or mass (particles far apart).
• Diffusion: Spreading of substance in air.

Elements

• Pure substance with one identical particle/molecule.
• Found on the Periodic Table.

Compounds

• Pure substance with two or more different types of particles/molecules bound together.
• Examples: Water $H<em>2O$, Carbon dioxide $CO</em>2$, Alcohol $C<em>2H</em>5OH$, Salt $NaCl$