1. Electricity at the Atomic Level
February 6, 2012

2. Objectives Define matter What is an atom? What are it’s components?
How are different elements distinguished from each other?
What are electrons, protons and neutrons. What kind of charges to they each have?
Describe negative and positive ions
Describe ionization
What are the symbols for current, volatage and resistance?

3. Electricity at the Atomic Level

4. The Components of an Atom

5. The Two Laws of Electrostatic Charges
Like Charges Repel
Unlike Charges Attract + + + + -
Proton
Electron

6. Atomic Number
The Number of Protons inside the nucleus of the atom determine the atomic number of the atom which is used to distinguish one element from another.

7. Shells & The Valence Shell
Electrons orbit the nucleus of the atom.
Each orbit is known as a shell.
The Valance shell is the outer most shell on any Atom.
The further away the valance shell is from the nucleus means it is easier for the atom to loose an electron.

8. Conductors/Insulators/Semiconductors
A conductor is a material which contains many free electrons. These are good materials for carrying an electric current.
An Insulator is a material which prevents the flow of electricity.
A Semiconductor is a material that is in the middle. It can be altered to become either an insulator or a conductor

9. Ionization
Atom - # protons = # electrons = Balanced
Atom - # protons < # electrons = negative Ion
Atom - # protons > # electrons = Positive Ion
The Process of gaining and loosing electrons is called ionization. This is a key part of current flow.

10. Current is represented by the symbol I
With some applied force, electrons will move from a negatively charged atom to a positively charged atom. This flow of electrons between atoms is called current.
Current is represented by the symbol I

11. Voltage is represented by the symbol E
When there is an abundance electrons at one end of a conductor and a lack of electrons at the other end, current will flow through the conductor. This difference in “pressure” is referred to as voltage.
Key Words/Terms:
Difference of Potential
Electromotive Force (EMF)
Voltage is represented by the symbol E

12. Resistance This is the opposition to the flow of electrons (current).
Every material offers some resistance.
Conductors offer very low resistance.
Insulators offer high resistance.
Resistance is represented by the Symbol R
Resistance is measured in Ohms Ω