Electrical Conductivity

1
Electrical Conductivity
2
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.

3
(No Transcript)
4
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.

5
Is 5 NaCl soltion a conductor?

• 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.

6
Ionic Bonds

• An ionic bond is typically formed between a metal
  and a non-metal. 
• 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.

7
Do covalent compounds conduct electricity?

• 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 electrons.  

8
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.

9
(No Transcript)
10
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.

11
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 particles
• The ability of these charged particles to move