General Chemistry CHEM 1103 Summer, 2003

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General ChemistryCHEM 1103Summer, 2003

• Nicholas H. Snow
• Department of Chemistry and Biochemistry
• Seton Hall University

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Course Structure

• MTR meetings 0815-1110
• lectures
• Discussion/problems
• Quizzes (0815 Thursdays)
• MTR Meetings 1130-1430
• Laboratory
• Laboratory meets in McNulty 321

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Course Structure, cont

• Four quizzes- 100 points each
• short answer, long answer
• Laboratory - 400 points
• Final - 200 points
• final will be multiple choice first semester ACS
  examination

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Study recommendations

• Study chemistry a few hours everyday cramming
  does not work!
• Study ahead, so that you know what is coming
• Ask Matt, Rafael and me questions!
• You should not have to study for the tests if you
  have properly prepared

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Chapter 1 - What is Chemistry?

• Science is the attempt to organize and study
  nature
• Chemists are interested in all matter
• Includes problems in material science and
  biochemistry
• micro- and nanoelectronics
• medicine
• green chemistry
• In particular
• properties of matter
• transformations of matter
• interactions of different types of matter

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Experimentation

• How we learn about matter and nature
• Chemistry can advance by
• deliberately planned courses of experimentation
• accidental discoveries
• Our experimentation and interpretation must be
  designed to be prepared for both possibilities
• Experimentation can also be driven by
  improvements in methodology and technology
  (better equipment and methods)

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Scientific method

• Hypothesis - initial idea about what matter will
  do
• Experiment - test of the hypothesis
• Theory - an explanation of what was observed
• Laws - statements summarizing observations (not
  explanations)

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Structure of matter

• Properties of matter
• macroscopic (can be seen with the eye)
• microscopic (underlying structure)
• Composition of matter
• atoms - basic unit of matter
• molecules - combinations of atoms
• There are a little over 100 types of atoms, but
  only about 20 are commonly encountered

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Chemicals

• Elements - types of atoms
• Compounds - substances composed of two or more
  different atoms in a definite proportion by mass
• Chemical formulas
• indicate the atoms in the compound
• number of each atom in the compound is designated
  by subscripts

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Periodic Table

• Elements demonstrated properties that repeated in
  a cyclical or periodic fashion
• Properties included both physical and chemical
• Gross organization of periodic table
• metals
• metalloids
• nonmetals

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Periodic Table

• Metals
• good conductors of heat, electricity
• shiny, malleable, ductile
• all solids except Hg
• Nonmetals
• properties are highly variable, but are generally
  poor conductors
• can be brittle solids, gases or liquids
• Metalloids
• often called semiconductors
• dull, brittle solids

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Families

• Rows are called periods
• Columns are called families
• alkali metals
• alkaline earths
• noble gases
• halogens
• chalcogens
• pnicnogens

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Characteristics of matter

• Elements - matter that cannot be broken down into
  simpler substances by chemical means
• Compounds - combinations of two or more different
  elements in definite proportion by mass
• Mixtures - combinations of matter that can be
  separated by physical means

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Phases of matter

• gas - particles of matter not in constant contact
  and are constantly moving
• does not have a specific shape
• does not have a specific volume
• liquid - particles are in constant contact, but
  are still in constant motion
• has a specific volume
• does not a definite shape
• Solid - particles are in contact and cannot move
  through the material
• has a specific volume and shape

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Mixtures

• homogenous - same throughout down to the
  molecular level often called a solution
• heterogeneous - contains regions or phases of
  different matter especially at the macroscopic
  level

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Physical properties

• can be measured without changing the substance
• those typically measured
• volume
• mass
• time
• temperature

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Measurement

• Scientific notation (do you know how to use your
  calculator?)
• Units
• prefixes (memorize them)
• SI and common metric units
• Dimensional analysis
• Precision - exactness of a measurement
• Accuracy - how close a measurement is to the
  true value

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Significant Figures

• number of digits expressed in a numerical value
• all nonzero digits are significant
• imbedded zeroes are significant
• zeroes used to hold place are generally not
  significant
• 12,000 - hard to say
• 0.0012 - zeroes here are not significant

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Calculations

• Physical properties are often measured that must
  be incorporated in calculations to yield
  chemically significant information
• Density is a good example

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Properties

• Extensive properties are those that depend on the
  amount of a substance
• mass and volume
• Intensive properties depend on the material and
  are independent of the amount of material
• density is a good example

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Precision in calculations

• Scientific measurements often require several
  measurements from more than one instruments
• This data is then used to calculate a quantity of
  interest
• For example, to measure density, one must measure
  mass and volume using two separate instruments

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Precision of calculations

• When adding or subtracting, the number of decimal
  places in the result is the number of decimal
  places in the number with the fewest places
• When multiplying or dividing, the number of
  significant figures in the result is the same as
  in the quantity with the fewest significant
  figures
• Postpone adjusting the result to the correct
  number of significant figures until the
  calculation is complete
• Remember, the calculator always gives you too
  many significant figures.