Electrical Nature of Matter

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Electrical Nature of Matter

• Grade Nine Science

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Question to Ponder

• What happens when you rub a balloon against your
  hair?
• Does this action create electric charges?

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What happens when you rub the balloon against
your hair?

• Both items have negative and positive charges.
• In fact, both items are said to be neutral
• Since the balloon and your hair are comprised of
  two different materials one item wants the
  negative charges more.
• One item becomes positive, the other negative
• Now each item is said to be charged.

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Electrostatics study of static electric charge.

• Static electricity (When Charges DO NOT Move).
• This is why the balloon can stick to the wall
• This is a result of The Law of Electric Charges
  

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The Law of Electric Charges

• Like charges repel one another, and unlike
  charges attract one another.
• How would you test for this?
• Place a known charge to an object with an unknown
  charge

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A Model for the Electrical Nature of Matter

• The Bohr-Rutherford model helps us understand how
  matter is structured and how it behaves.
• The main ideas of this model are presented on the
  next couple of slides.

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A Model for the Electrical Nature of Matter

• All matter is made up of particles called atoms.
• At the centre of each atom is a nucleus, with two
  kinds of particles the positively charged proton
  and the uncharged neutron. Protons do not move
  from the nucleus when an atom becomes charged.

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A Model for the Electrical Nature of Matter

• Negatively charged particles called electrons
  surrounds the nucleus. When atoms become
  charged, only the electrons move from atom to
  atom.
• Like charges repel each other unlike charges
  attract each other.
• Some elements have a weaker attraction for its
  electrons than others and the electrons are able
  to move freely from atom to atom. A good example
  is copper

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A Model for the Electrical Nature of Matter

• A single atom is always electrically neutral.
• If an atom gains an extra electron, the net
  charge on the atom is negative and it is called a
  negative ion. If an atom loses an electron, the
  net charge on the atom is positive and it is
  called a positive ion.

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Negative Ions

• If an atom gains an extra e-, the net charge on
  the atom is negative , and it is called a
  negative ion .
• 6 protons (6) 6
• 6 electrons (6-) 7-
• Neutral 0 (no charge) 1- (-ion)

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Positive Ions

• If an atom loses an extra e-, the net charge on
  the atom is positive , and it is called a
  positive ion .
• 6 protons (6) 6
• 6 electrons (6-) 4-
• Neutral 0 (no charge) 2 (ion)

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Homework

• Page 273 questions 1-5