The Atom and subatomic Particles

1
Introduction
2
Early Universe

• About 13.7 billion years ago - Big Bang
• Created hydrogen and helium and just a little bit
  of lithium
• Other elements created in the nuclear engines of
  stars
• Exploding stars - supernova - spread the elements
  around the universe

3
The Small World

• At sea level, one cubic inch of air (about the
  size of a sugar cube) contains 45 billion billion
  molecules

4
The Small World

• At sea level, one cubic inch of air (about the
  size of a sugar cube) contains 45 billion billion
  molecules
• Divide a millimeter into 1000 equal parts 1
  micron Now divide a micron into 10,000 parts
  thats the scale of an atom (1/10,000,000 of a mm)

5
The Small World

• Every atom of your body has almost certainly
  passed through several stars and been part of
  millions of organisms on its way to you.

6
The Atom and sub-atomic Particles
Oxygen Atom - Atomic 8
(-)electrons
() protons (0) neutrons
7
electrons

• Electron clouds surround the atom nucleus in
  discrete shells
• The cloud is a zone of ...statistic probability,
  marking the area beyond which the electron only
  very seldom strays. B.B. 2003

8
Electrical Charges

• electrons are negative ( )
• protons are positive ()
• neutrons have no charge (0)
• unlike charges attract each other
• like charges repel each other
• in a neutral atom,
• electrons protons

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A Molecule is made up of Atoms
10
Valence
valence electron in outer shell
Copper Atom (Cu)
29
11
Ion

• when an atom loses or gains an electron
• takes energy to do this chemical, light, heat,
  etc.

12
Where does electricity come from?

• Electrical charges are naturally occurring in
  all conducting materials
• Batteries, generators, etc. act like pumps that
  move the charges

13
Where does electricity come from?

• Mechanical sources - generators using relative
  motion between coils of wire and magnetic fields
• Chemical sources - batteries, fuel cells
• Pressure (Piezoelectric) - quartz crystal
• Heat - thermocouple
• Light - photovoltaic

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Valence
4 valence electrons in outer shell
Silicon Atom (Si)
14
15
Potential Difference

• What makes the electricity world go round!
• two points that have a different charge (one ,
  one -) because energy has created ions by
  stripping electrons from atoms creating ions
• or, adding an electron, creating -ions

16
Unit of Charge

• Coulomb is the unit of charge represented by 6.25
  x 10 electrons
• Established by Charles Coulomb - French Scientist
  (1736-1806)
• Defines the attraction and repulsion of charged
  particles (electrons)

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17
Unit of Charge

• In wires, moving charges are electrons
• But in batteries, in the air, etc., moving
  charges can be positive ions