SCN1D/ ELECTRICITY UNIT
Unit D: ATOMS , ELEMENTS AND
COMPOUNDS
OVERALL CURRICULUM EXPECTATIONS
• E1. Assess some of the costs and benefits associated with the
production of electrical energy from renewable and nonrenewable sources, and analyse how electrical efficiencies and
savings can be achieved, through both the design of technological
devices and practices in the home;
• E2. Investigate, through inquiry, various aspects of electricity,
including the properties of static and current electricity, and the
quantitative relationships between potential difference, current,
and resistance in electrical circuits;
• E3. Demonstrate an understanding of the principles of static and
current electricity.
SPECIFIC EXPECTATIONS
11.1 WHAT IS STATIC
ELECTRICITY?
SNC1D
RECALL: ATOMIC STRUCTURE
Recall the 3 subatomic particles studied in chemistry:
protons
have a positive (+) charge
electrons
have a negative (-) charge
neutrons
have no (0) charge
• The 2 subatomic particles contained in the nucleus are protons
and neutrons.
• Unlike protons and neutrons, electrons have the ability to move
around and be removed from the atom.
ELECTRIC CHARGE
• If an atom has an unequal number of protons and electrons, it
has an electric charge which will exert and electric force
(repulsive or attractive).
• A neutral object has an equal number of protons and electrons
• A negatively charged object has more electrons than protons
• A positively charged object has more protons that electrons.
Examples: positive, negative, or neutral?
ELECTRONS MOVE!
• Objects may become electrically charged when electrons are
transferred to or from another object.
• Gaining electrons will make an object more negatively charged
while losing electrons will make an object more positively
charged.
• Most of the objects we deal with on a daily basis are electrically
neutral.
When 2 neutral objects of different
materials come in contact electrons can be
transferred from one object to the other. Now
both objects are charged. This creates
STATIC ELECTRICITY:
An imbalance of electric charge on the
surface of an object.
THE LAW OF ELECTRIC CHARGES
• A charged object exerts an electric force, which can
be either an attractive force (pulling together) or
repulsive force (pushing apart).
The Law of Electric Charges
states:
• OBJECTS OF LIKE
CHARGES REPEL EACH
OTHER
• OBJECTS OF OPPOSITE
CHARGES ATTRACT EACH
OTHER
THE LAW OF ELECTRIC CHARGES
• Examples:
Ebonite negatively
charged
Pith ball negatively
charged
Ebonite negatively
charged
Pith ball positively
charged
What happens when a charged object is
brought towards a neutral object?
• When a charged object is brought near a neutral object it causes (induces) the
electrons to shift in position.
• The induced movement of electrons in a neutral object by a nearby charged object is
called an INDUCED CHARGED SEPARATION. The movement of electrons occurs
according to the law of electric charges.
Induced Charge Separation: a shift in the position of electrons in a
neutral object that occurs when a charged object is brought near it.
Detecting electric charges: pith ball electroscope
• Pith is a plant material that can be
used to test for the presence and type
of electric charge on an object.
• If the object is charged, the pith ball
will be attracted to it.
Detecting electric charges: metal leaf electroscope
• The metal leaf electroscope is more sensitive to
electric charge than a pith ball. The metal “leaves”
are usually gold or aluminum.
HOMEWORK
• READ PG. 465- 470
• MAKE NOTES ON
ELECTROSTATIC PAINT
SPRAYERS IN THE
DESIGNATED SECTION ON
YOUR HANDOUT
• ANSWER PG. 471 #2-7, 9
END OF WEEK 6 / CLASS 1