Electricity

9.2 The Electrical Nature of Matter

• Electricity web• What do you know about

electricity?• What do you want to know?• How will you find out?• What is electricity? (handout)• Electrons pass from atom to atom

creating an electrical current from one end to the other.

• Balloon demo.

The Electrical Nature of Matter• All the atoms in matter always

contain electrical charges. We are unaware, however, of these charges in a balloon or in our hair, until we make them move.

• Some articles remain charged for a short period of time (static on a shirt), while other items such as satellites in space, are charged for a long time.

• On many common substances the charge remains “STATIC”, in other words, the charge stays where the rubbing occurred. This has come to be known as static electricity.

• The study of static electric charge is called “electrostatics”.

• There are two kinds of electric charge: Positive and Negative. When two different neutral substances are rubbed together, one becomes negative and one positive.

The Law of Electric Charges states:• Two objects with like charges,

whether positive or negative, always repel one another.

• When a positive object is brought near a negative, the objects attract, “OPPOSITES ATTRACT”.

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Attraction Repulsion

Negative ion• Bohr Rutherford models show how

matter is structured and how it behaves.

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)

P=3N=3

Electrons orbit the nucleus

Protons and Neutrons in the nucleus

Positive ionIf 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)

Questions• P.273 #1 & 5