Transcript Electrical Conductivity

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
Tongue
Depressor
Tongue
Back View
Depressor
LED
Light
Electrical Tape
Resistor
Solder
9 volts
Electrical
Tape
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
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.
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.
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.
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
particles
• The ability of these
charged particles to move