Chapter 1 Chemistry: An Introduction

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Chapter 1Chemistry An Introduction
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What is Chemistry?

• The study of the matter, its composition,
  properties, and the changes it undergoes.
• Applied Chemistry is the using chemistry to
  attain certain goals, in fields like medicine,
  agriculture, and manufacturing
• Pure chemistry gathers knowledge for knowledge
  sake

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Types of Chemistry

• Analytical Chemistry studies composition of
  substances.
• Inorganic Chemistry substances without carbon
• Organic Chemistry compounds containing carbon
• Biochemistry- Chemistry of living things
• Physical Chemistry studies behavior of substances

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Chemistry is

• A natural science.
• a language with its own vocabulary.
• a way of thinking.

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Scientific Method

• A way of solving problems or answering questions.
• Starts with observation- noting an recording
  facts
• Hypothesis- an educated guess as to the cause of
  the problem or answer to the question.

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Scientific Method

• Experiment- designed to test the hypothesis
• only two possible answers
• hypothesis is right
• hypothesis is wrong
• Generates data observations from experiments.
• Modify hypothesis - repeat the cycle

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• Cycle repeats many times.
• The hypothesis gets more and more certain.
• Becomes a theory
• A thoroughly tested model that explains why
  things behave a certain way.

Observations
Hypothesis
Experiment
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• Theory can never be proven.
• Useful because they predict behavior
• Help us form mental pictures of processes (models)

Observations
Hypothesis
Experiment
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• Another outcome is that certain behavior is
  repeated many times
• Scientific Law is developed
• Description of how things behave
• Law - how
• Theory- why

Observations
Hypothesis
Experiment
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Observations
Hypothesis
Experiment
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Experiment

• Scientists use an experiment to search for cause
  and effect relationships in nature.
• In other words, they design an experiment so that
  changes to one item cause something else to vary
  in a predictable way.

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Variables

• Variableschanging quantities in experiment
• An experiment usually has three kinds
  independent, dependent, and controlled.
• The independent variable is the one that is
  changed by the scientist.
• Experiment has only one independent variable.
  Independent variable are changed to observe what
  happens.

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• Dependent variable changes in response to the
  change maked to the independent variable.
• The new value of the dependent variable is caused
  by and depends on the value of the independent
  variable.
• For example, if you open a faucet (the
  independent variable), the quantity of water
  flowing (dependent variable) changes in
  response--the water flow increases.

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• Controlled variables are quantities that a
  scientist wants to remain constant, and he must
  observe them as carefully as the dependent
  variables.
• For example, if we want to measure how much water
  flow increases when we open a faucet, it is
  important to make sure that the water pressure
  (the controlled variable) is held constant.
  That's because both the water pressure and the
  opening of a faucet have an impact on how much
  water flows.