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Chemistry: The Study of Matter

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What is Chemistry?

 The study of the matter, its composition, properties, and the changes it undergoes.

 Applied Research or Applied Chemistry is the using chemistry to attain certain goals, in fields like medicine, agriculture, and manufacturing.

 Basic Research or Pure Research gathers knowledge for knowledge’s sake

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Chemistry is

 a natural science.

 a language with its own vocabulary.

 a way of thinking.

Scientific Method

5  Is a way of solving problems or answering questions.

 Starts with observations and recording facts.

 Hypothesis- an educated guess as to the cause of the problem or poses an 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

7 Observations Hypothesis Experiment  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.

8 Observations Hypothesis Experiment  Theory can never be proven.

 Useful because they predict behavior  Help us form mental pictures of processes ( models )

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

10 Observations Hypothesis Experiment Law Theory (Model) Prediction

Modify

Experiment

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What is Matter?

 Matter is anything that takes up space and has mass.

 Mass is the amount of matter in an object.

 Mass is resistance to change in motion along a smooth and level surface.

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Properties

 Words that describe matter (adjectives)  Physical Properties - a property that can be observed and measured without changing the substance.

 Examples?

 Chemical Properties - a property that can only be observed by changing the type of substance.

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Physical Changes

 A change that changes appearances, without changing the composition.

 Examples?

 Boiled water is still water.

 Chemical change - a change where a new form of matter is formed.

 Examples?

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Chemical Reactions

 When one or more substances are changed into new substances.

 Reactants- stuff you start with  Products- What you make  NEW PROPERTIES  Not easily reversed

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Indications of a chemical reaction

 Energy absorbed or released  Color change  odor change  Precipitate - solid that separates from solution  Not easily reversed

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Conservation of Mass

 Mass can not be created or destroyed in ordinary (not nuclear) changes.

 All the mass can be accounted for.