Electrical Conductivity by aAVJC3


									TEKS Objective

(6) The student knows the impact
  of energy transformations in
  everyday life.
 The student is expected to:
 (E) measure the thermal and
      electrical conductivity of
      various material and explain
      the results.
Front View                  Back View
Tongue             Tongue
Depressor                   Depressor

                                           Electrical Tape


 9 volts
                                                     Battery Clip

                                           Electrical Tape

                                          Wires with insulation stripped off
Is NaCl a conductor?

• NaCl does not conduct
  electricity as it is. NaCl is an
  ionic compound and both the
  Na+ and the Cl- are strongly
  attracted to each other by
  electrostatic action. The flow of
  charge is not possible.
Is 5% NaCl soltion a
• Yes, water molecules separate
  the Na+ and the Cl- ions. This
  makes them very mobile. The
  mobility is enhanced when the
  two electrodes in the form of
  anode and cathode are inserted
  in the salt solution. This type of
  solution is called an electrolyte.
  Ionic Bonds
• An ionic bond is typically
  formed between a metal and a
• Consequently, the non-metal is
  "stronger" than the metal, and
  can steal electrons very easily
  from the metal.
• This results in the metal
  becoming a cation, and the
  non-metal becoming an anion.
• An ionic bond is the
  resulting attraction for an
  anion and a cation after an
  electron is transferred from
  the metal to the non-metal.
Do covalent compounds conduct
• A covalent bond does not
  allow electrons to move
  freely within the body of
  the object.
• A covalent bond is
  typically formed by two
  non-metals. Neither atom
  is "strong" enough to
  steal electrons from the
  other. Therefore, the
  atoms must share the
How does electricity flow in metal?
• In metals, free
  electrons carry the
  current. In metal wire,
  all the atoms share
  the electrons in their
  outermost electron
  shell and these
  electrons are free to
  move anywhere
  within the wire.
What is the purpose of
the battery?
The battery supplies electrons
which flow from the negative
end where there are many
electrons to the positive end
where there are few electrons.
Learning Goal

• In this investigation
  students learn that the
  ability of a material to
  conduct an electric current
  is dependent upon:
   • The presence of charged
   • The ability of these
     charged particles to move

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