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Electron Theory
Introduction
 Structure and Matter
 Atoms and Molecules
 Atomic Structure
 Electron Flow

Introduction
Structure and Matter
In this section we will discuss the concept
of Matter.
Structure and Matter
Matter
Definition: Anything that occupies space and
has mass.
Structure and Matter

Matter
 Can
be solid, liquid or gas
Ice
 Water
 Air

Structure and Matter

Matter
 Can
be solid, liquid or gas
 Can be element, compound, or mixture
Structure and Matter

Matter
 Can
be solid, liquid or gas
 Can be element, compound, or mixture

Element- Is the basic building block of nature

Purest form of matter. Can not be divided into simpler
substances (see periodic table)
 Hydrogen
 Oxygen
 Carbon
Structure and Matter

Matter
 Can
be solid, liquid or gas
 Can be element, compound, or mixture
Element- Is the basic building block of nature
 Compound- Two or more chemically combined
elements


Contain the same proportion throughout
 CO2
 H 2O
Structure and Matter

Matter
 Can
be solid, liquid or gas
 Can be element, compound, or mixture
Element- Is the basic building block of nature
 Compound- Two or more chemically combined
elements
 Mixture- Two or more elements not chemically
combined, (proportion may vary).


i.e. Saltwater, Sand and Gravel
Atoms and Molecules
Atom
 Molecule
 Molecular Compound
 Ionic Compound

Atoms and Molecules

Atom- Smallest part of an element that
retains the properties of that element
 Electrons
 Neutrons
Electrons
 Protons
Nucleus contains
Protons & neutrons
Atoms and Molecules

Atom
 Electrons

Negative charge (-)
 Neutrons
Electrons
 Protons
Nucleus contains
Protons & neutrons
Atoms and Molecules

Atom
 Electrons
 Neutrons
Neutral charge
 within the nucleus

 Protons
Electrons
Nucleus contains
Protons & neutrons
Atoms and Molecules

Atom
 Electrons
 Neutrons
 Protons
Positive charge
 Within nucleus
Electrons

Nucleus contains
Protons & neutrons
Atoms

Have a Nucleus
 Protons
(positive charge)
 Neutrons (neutral charge)

Orbiting electrons (negative charge)
Bohr Model (Hydrogen)
Electron
Nucleus
(1 proton 1 neutron)
N=1
H
Bohr Model (Helium)
Electron
Nucleus
(2 protons 2 neutrons)
N=1
He
Electron
Bohr Model (Lithium)
1 valence electron
Nucleus
(3 protons 4 neutrons)
N=1
N=2
Li
Bohr Model
The number of electrons in each shell is determined by the formula:
#electrons=2n2
Bohr Model (Copper)
1 valence electron
N=1=2(1)2=2
N=2=2(2)2=8
N=3=2(3)2=18
N=4=2(4)2=32
60
Nucleus
(29 protons 35 neutrons)
N=1
N=2
N=3
N=4
Cu
Copper Element
29
Cu
Copper
63.54
Copper Element
29
Cu
Copper
63.54
Name
Copper Element
Atomic Number
29
Cu
Copper
63.54
Name
Copper Element
Atomic Number
29
Cu
Copper
63.54
Chemical
Symbol
Name
Copper Element
Atomic Number
29
Cu
Copper
63.54
Atomic Weight
Chemical
Symbol
Name
Electrons charge
The charge of 1 electron = 1.602x10-19
Coulombs
Or
 1 Coulomb = 6.24x1018 electrons

Electrons excitation
Electrons will stay in orbit as long as the
bond is present between the electron
and the protons
Cu
Electrons excitation
When energy is present enough to
break the proton and electron’s bond,
the electron will release from the atoms
outer most (valence) shell.
Light,
Heat,
or
EMF
Cu
Electrons excitation
Direction of electron flow is produced
when positive forces are strong enough
to pull electrons in a direction.
-
+
Cu
Cu
Cu
Cu
Electrons excitation
Recall
 1 Coulomb = 6.24x1018 electrons
That’s a heck of a lot of
electrons!!!!
6,240,000,000,000,000,000 to be exact!!!!
Electrons Flow

Current = The directional flow of
electrons from a negative to positive
Electrons Flow

1 Amp = the amount of 1 coulomb of
18
electrons (6.24x10 ) crossing an area
per second
_
+
6.24x1018 electrons/second
Electrons Flow

This is defined as Current Flow “I”
through a conductor
_
+
6.24x1018 electrons/second
Electrons Flow

If we were to say that 2 Amps is flowing
in the conductor the # of electrons is
(6.24x1018) x 2 and so on…..
_
+
6.24x1018 electrons/second
Electrons Flow

In an ideal world, current flow (electron
movement) through a conductor would
not have any resistance.
_
+
6.24x1018 electrons/second
Electrons Flow

As we shall see later, this is not the
case.
_
+
6.24x1018 electrons/second
Electrons Flow

Until then simply understand current
flow is the movement of electrons
through a conductive material
_
+
6.24x1018 electrons/second
Practice Problem:
If a copper wire has 50mA of current flowing through it, how many
electrons are passing through a single cross-sectional area each
second?
Practice Problem:
If a copper wire has 50mA of current flowing through it, how many
electrons are passing through a single cross-sectional area each
second?
Solution:
(6.24x1018)x.05 = 3.17x1017 electrons/second
End of Presentation