Chapter 1: The Nature of Science

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Chapter 1 The Nature of Science
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What is Science?

• Life, Earth and Physical Science

Matter and Energy
Living things
Chemistry
Earth and Space
Physics
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Steps to the Scientific Method

• Observation ? a question
• Gather Info
• Hypothesis a tentative answer
• Experiment test the hypothesis
• Conclusion

• Observation ? a question
• Gather Info
• Hypothesis a tentative answer
• Experiment test the hypothesis
• Conclusion

If doesnt work
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Variables and Constants

• Variable - Things that are changing
• Constants Things that are NOT changing
• Control A test that is left alone. Nothing is
  done in this test.

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Conclusions

• Scientific law describes how nature behaves.
  Normally is always true.
• Theory explains why nature behaves in the way
  described by the law. Predicts results of
  further experiments.

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Now Lets use this Method

• Observation ? a question
• Gather Info
• Hypothesis a tentative answer
• Experiment test the hypothesis
• Conclusion

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Whats in Frankensteins Head??

• Read the handout
• Record your observations
• Draw a diagram of your model
• Have your final model approved
• Answer final questions

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Classification of Matter

• Chapter 15

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Composition of Matter Sec. 1

• Pure Substances
• Same composition throughout
• Either an element or compound
• Element
• All one type of atom
• Everything made of atoms
• Compound
• Atoms of two or more elements chemically bonded
  together

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Composition of Matter

• Mixtures
• Made of two or more substances that can be easily
  separated by physical means
• Heterogeneous Mixture
• Different materials can be seen easily
• Granite, concrete, vegetable soup
• Homogeneous Mixture (Solution)
• Blended evenly throughout
• Vinegar, Kool-aid

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MATTER
Can it be separated?
no
yes
Substance
Mixtures
Homogeneous Mixture Air, sugar water, stainless
stell
Heterogeneous Mixture Granite, wood, blood
Compounds Water, sodium chloride
Elements Gold, aluminum
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Mixtures

• Colloid heterogeneous
• Particles larger than solution but not heavy
  enough to settle out
• Milk, paint, fog and smoke
• Detecting Colloids
• Pass a beam of light through it
• Colloid See beam
• Solution Cannot see beam
• Particles big enough to scatter light Tyndall
  Effect

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Mixtures

• Suspension heterogeneous
• Not solution, not colloid
• Muddy pond water
• Heterogeneous mixture with a liquid and visible
  particles that settle

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Properties of Matter

• Section 2

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Physical Properties

• Def characteristic observed without changing the
  identity of the material
• Ex color, shape, size, density
• Appearance
• Behavior
• Magnetic, malleable, flow of liquid

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Separating Mixtures

• Sand and Rock mixture?
• Filter or sift
• Iron filings and Aluminum mixture?
• Magnet

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Physical Change

• Change in size, shape or state of matter and
  identity is same
• Solid to a liquid?
• Yes

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Liquid
Gas
Solid
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Physical Change

• How to get pure water from salt water?
• Distillation evaporate liquid and then
  recondense it

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Chemical Properties and Changes

• Chemical Property can be observed only by
  changing the substance
• Flammability, reactivity, decomposition
• Chemical Change change where a NEW substance is
  formed
• Weathering Physical or Chemical Change?
• Both!

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Law of Conservation of Mass

• Matter is neither created nor destroyed during a
  chemical reaction
• Mass of all substances before mass of all
  substances after change