Principles, Models, Theories

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Principles, Models, Theories Laws
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10 Principles of Science

• 1. Principle of Objectivity-
• Scientists base all conclusions on facts
• 2. Principle of Tentativeness-
• Scientists are willing to modify their
  conclusions if new evidence disproves them
• 3. Principle of Consistency-
• Scientists assume that laws and the relationships
  they refer to remain consistent

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10 Principles of Science

• 4. Principle of Causality
• Scientist believe that every phenomenon results
  from discoverable causes
• 5. Principle of Parsimony
• Scientists view the world in the simplest terms
  possible
• 6. Principle of materiality
• Scientists prefer material and mechanical
  explanations of phenomena

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10 Principles of Science

• 7. Principle of Relativeness
• Scientists think of the world as consisting of
  sets of relationships
• 8. Principle of dynamism
• Scientists expect nature to be dynamic and
  changing
• 9. Principle of Continuous discovery
• Scientists hope that they can discover something
  previously unknown
• 10. Principle of Social Limitation
• Scientists work within a social framework- for
  the good of all

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Models

• Scientific model mental picture or description
  of something that
• cannot be directly observed
• e.g.
• Model of an atom
• Model of a black hole

Billiard ball model of an atom
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Models

• Good models
• Explain characteristics of the concept or idea
  they represent
• Can be used to make predictions about behaviors
  or responses in new situations
• Can be tested

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Testing Models

• Daltons model could not explain electron
  movement
• Replaced by Thompsons

Billiard ball model

• Thompsons model could not explain deflection of
  radiation particles
• Replaced by Rutherfords model

Muffin/ Plum pudding Model

• Rutherfords could not explain light emission by
  excited electrons
• Replaced by Bohrs model

Rutherford model
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Theory

• Theory - a set of principles that explain a
  scientific finding or phenomena.
• Scientists create theories using scientific
  method
• When first proposed hypothesis
• Tested for accuracy through experimental
  observation
• Once a hypothesis is verified by repeated testing
  it becomes a theory

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Scientific Theory

• Theory may be used to explain laws
• Atomic Theory can be used to explain the Law of
  Conservation of Mass. Atoms change partners in a
  chemical reaction, none are created and none are
  destroyed

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Theories explain Laws

• Atomic Theory explains the Law of Conservation of
  Mass.

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Law

• A scientific law is a statement
• describing a phenomenon in the
• universe
• A scientific law cannot be broken
• -does not explain why

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Law

• Based on results of repeated testing of a
  hypothesis
• E.g.
• Law of Gravity all objects with mass are
• attracted to one another
• Law of inertia objects in motion stay in motion,
• objects a rest stay at rest
• Law of conservation of mass in a chemical
• reaction, the mass of the reactants is equal to
  the
• mass of the products

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