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					UNIT 1 – WHAT IS
 CHEMISTRY?
Essential
Questions:
 Why is lab safety important?
 How do we classify matter?
 How do we classify energy?
 How can mixtures be separated?
Objectives

 To define chemistry
 To compare and contrast the different
  branches of chemistry
 To understand scientific thinking
 To use experiments to solve a scientific
  problem
Chemistry

 Study of the composition, structure, and
  properties of matter
 Changes in matter
 Changes in energy
Branches of
Chemistry
 Organic
 Inorganic
 Biochemistry
 Physical
 Analytical
The Scientific
Method
 Used for solving a scientific problem
 Involves:
 •   Observing and collecting data
 •   Forming a hypothesis
 •   Developing a theory supported by data
The Scientific
Method
 If data from experiments are true,
 scientists try to explain the phenomena
 by constructing a model.
 From there, a theory can be formed
The Scientific
Method
Controlled
Experiments
 A Controlled Experiment is one where only
  one variable is tested at a time

 Why is it important to use controlled
  experiments?
Controlled
Experiments
 Control Group – the group that doesn’t
  receive the experimental treatment, a
  standard for comparison
 Independent Variable – the variable in the
  experiment you change
 Dependent Variable – the variable in the
  experiment that only changes because
  you changed the independent variable
Controlled
Experiments
 Example:
   Merck decides to test a new antibiotic to see if
    it will cure patients’ sinus infections. Some
    testers are given pills containing the new
    antibiotic and others are given a placebo, or
    sugar pill.
 Identify:
   Control
   Independent Variable
   Dependent Variable
Objectives

 To learn about the composition of matter
 To the learn the difference between
  compounds and elements
 To define the states of matter
 To learn methods of separating matter
 To learn the names and symbols of
  elements
Classification of
Matter
 Matter – occupies space and has mass
 Four states:



                           Do not worry
                           about the
                           changes from
                           one state of
                           matter to the
                           other just yet…
Classification of
Matter
Classification of
Matter
 Solution – a term for a homogeneous
  mixture
 Alloy – a homogeneous mixture of two or
 more metals
Classification of
Matter
 Pure substances can be divided into the
  smallest piece that still retains the
  properties of that substance
 If smallest piece is an atom, then it is an
  element
 If smallest piece is a molecule or formula
  unit, then it is a compound
Classification of
Matter
Element Names and
Symbols
 Symbols of most common elements use
  first letter (mainly nonmetals)
 Some use first and second letter
 Some use first letter and first
  consonant
 Jons Jacob Berzelius – based chemical
  symbols on the Latin name of the
  element
 Latin Name   Symbol     Name
   Kalium       K      Potassium
   Ferrum       Fe        Iron
   Cuprum       Cu      Copper
  Argentum      Ag       Silver
  Stannum       Sn         Tin
   Stibium      Sb     Antimony
   Wolfram      W      Tungsten
   Aurum        Au       Gold
Hvdrargyrum     Hg      Mercury
  Plumbum       Pb       Lead
   Natrium      Na      Sodium
Techniques For
Separating Mixtures
 Filtration
 Distillation
 Paper Chromatography
Filtration
Distillation
Paper
Chromatography
Objectives

 To distinguish between intensive and
  extensive properties
 To distinguish between physical and
  chemical properties
 To distinguish between physical and
  chemical changes
Describing Matter

 Extensive properties – depend on the
 amount of matter
 Intensive properties – depend on the
 type of matter , not the amount
Describing Matter

 Physical Properties
   Can usually be observed by our senses
Describing Matter

 Chemical properties
   Can be observed in regard to whether or
   not a substance reacts with another
   substance.
Describing Matter

 Physical Changes
   Alter the physical property of matter, but
   composition remains constant
Describing Matter

• Chemical Changes
 • Changes in composition and structure

 • Always accompanied by energy changes

 • Also called reactions
Chemical Changes

 During a chemical reaction, mass of
 products equals mass of reactants
 Law of Conservation of Mass
• In any physical or chemical change,
 mass is conserved.
Objectives

 To understand the general properties of
  energy
 To classify different forms of energy
Energy

 Energy – capacity to do work
 Can be expressed in joules or
 kilocalories
 1 kilocalorie (Calorie) = 4.184 joules
Classification of
Energy
 Different Forms:
   Thermal (heat)
   Light
   Sound
   Mechanical
   Electrical
   Chemical
Thermal Energy
(Heat)
 Energy transferred from one body to
  another
Light

 Nature’s way of transferring energy
  through space
Sound

 Energy produced by sounds through a
  medium
Mechanical Energy

 Sum of kinetic and potential energy in a
  system
General
Classifications
 Potential energy – due to position
 Kinetic energy – due to motion
Electrical Energy

 Made available through the flow of an
  electrical charge through a conductor
Chemical Energy

 Energy stored within the bonds of a
  molecule

				
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