Electrical Principles
Chapter 1
Matter, Atoms, Conductors,
Insulators, SemiConductors,
Elements, Molecules,
Compounds, and Electron Flow
Matter
Matter
What is Matter?
 Matter is anything that has mass and
occupies space.
 Matter can exist in a state of gas, liquid,
or solid.
Matter
A Solid is a state of matter that has a
definite shape and volume.
 A Liquid is a state of matter that a definite
volume but not a definite shape.
 A Gas is a state of matter that is fluid, has
a relatively low density, and is highly
compressible.

Matter
All Matter has electrical properties.
 Electrical Behavior of matter varies
according to the physical makeup of the
matter.
 Some Matter allows electricity to flow
through it more easily. This type of Matter
is called a Conductor. Examples: Copper

Matter
A Conductor is a material that has very
little resistance and allows electricity to
flow easily through it.
 Material that does not allow electricity to
flow easily is called an Insulator.
 An Insulator is a material that has very
high resistance and restricts the flow of
electricity. Example: Glass, Rubber,
Plastic, Paper

Questions!?!?!?!?!
Atoms
Atoms
The word Atom is a Greek word meaning
a particle that is too small to subdivide.
 Neils Bohr, A Danish Physicist, Put forward
a theory in 1913 about the atom and the
subatomic particles that make up the
atom. This model is still in use today.
 Bohr’s atomic structure model combines
the ideas of Planck, Rutherford, and
Einstein.

Atoms
An Atom is the smallest particle that an
element can be reduced to and still
maintain the properties of that element.
 Three principal parts of the Atom are:
Electron
Neutron
Proton

Atoms
An Electron is a negatively charged
particle in an Atom.
 A Neutron is a neutral particle, with a
mass approximately the same as a proton,
that exists in the nucleus of an Atom.
 A Proton is a particle with a positive
electrical charge of 1 Unit that exists in the
nucleus of the Atom.

Atoms
Atoms



The electrons orbit the
nucleus of an atom.
The neutron and proton
combine to form the
nucleus.
The Atomic Number of
an Atom describes the
number of protons that
exist within the nucleus.
Atoms

The number of neutrons
within an atom’s nucleus
can be calculated by
subtracting the atomic
number (protons) from the
atomic weight (combined
protons and neutrons).
Atoms

Example – Beryllium has
an Atomic Number of 4
(Protons) and an Atomic
Weight of 9 (Protons and
Neutrons). Subtracting the
beryllium atoms weight (9)
from the Atomic Number
(4), we can determine the
number of neutrons to be
5.
Atoms

A Neutral Atom or Balanced Atom is an atom
that has an equal number of protons and
orbiting electrons, so the net positive proton
charge is equal but opposite to the net negative
electron charge, resulting in a balanced or
neutral state.
Atoms

Orbiting electrons travel around the nucleus at
varying distances from the nucleus and these
orbital paths are known as shells or bands.
The orbital shell nearest the nucleus is referred
to as the first or K shell. The second is known
as the L shell, the third is M, the fourth is N, the
fifth is O, the sixth is P, and the seventh is the Q
shell. The outer most electron occupied shell is
known as the Valence Shell or Ring and
electrons in this shell are termed Valence
Electrons.
Atoms
Atoms
Laws of Attraction and Repulsion or Law of
Charges
 Like charges repel one another.
(Like Charges are positive and positive or
negative and negative).
 Unlike Charges attract one another.
(Unlike Charges are positive and
negative or negative and positive).
Atoms
Laws of Attraction and Repulsion or Law of
Charges
 Positively charged particles attracts a
negatively charged particle
 Positively charged particles repels against
another positively charged particle.
 Negatively charged particles repel another
negatively charged particle.
Atoms
Laws of
Attraction
and
Repulsion
or
Law of
Charges
Atoms



Laws of Attraction and Repulsion or Law of
Charges
Orbiting negative electrons are attracted toward
the positive nucleus.
Orbiting electrons remain in a stable orbit due to
two equal but opposite forces.
The centrifugal outward force exerted on the
electrons due to the orbit counteracts the
attractive force trying to pull the electrons toward
the nucleus due to the unlike charges.
Atoms
Laws of Attraction and Repulsion or Law of
Charges


Due to the distance from the nucleus, valence
electrons are described as being loosely bound
to the atom.
These electrons can easily be dislodged from
their outer orbital shell by any external force, to
become a Free Electron.
Atoms
Laws of Attraction and Repulsion or Law of
Charges
 The gaining or losing of electrons
produces and electric charge in the atom.
 All charges particles exert forces on one
another, even if they are not in physical
contact.
 The exerted force is due to the electric
field that surrounds all charged particles.
Valence Electrons



A Valence Shell is the outermost shell of an
atom and contains the electrons that form new
compounds. Example – two hydrogen atoms
combine with the electrons in the outer shell of an
oxygen atom to form water (H2O).
The electrons in the Valence Shell are important
because they can be used to produce an electric
current flow.
The number of electrons in the Valence Shell
determines whether the material is a Conductor,
SemiConductor, or Insulator.
Questions!?!?!?!?!
Conductors, Insulators and
SemiConductors
Conductors, Insulators and
SemiConductors


A Conductor is a material
that has very little
resistance and allows
electricity to flow easily
through it. Conductors
have three or less
valence electrons.
Electricity is flowing
through the electrons of
the outer most Valence
Shell into the electrons of
the adjoining atom’s
Valence Shell outer most
electrons.
Conductors, Insulators and
SemiConductors
Material that does not allow electricity to
flow easily is called an Insulator.
 An Insulator is a material that has very
high resistance and restricts the flow of
electricity. Example: Glass, Rubber,
Plastic, Paper
 Insulators have five or more valence
electrons.

Conductors, Insulators and
SemiConductors



A SemiConductor is an electronic device that
has electrical conductivity between that of a
conductor (high conductivity) and that of an
insulator (low conductivity).
SemiConductors, such as carbon, germanium,
and silicon, are made from materials that have
exactly four valence electrons.
SemiConductor materials do not conduct
electricity easily and are not good insulators.
Questions!?!?!?!?!
Elements, Molecules and
Compounds
Elements, Molecules and Compounds
An atom is the smallest unit of a natural
element, or an element is a substance
consisting of a large number of the same
atom.
 Combinations of elements are known as
Compounds and the smallest unit of a
compound is called a Molecule.
 Water is an example of a liquid compound
in which the Molecule (H2O) is a
combination of an explosive gas
(hydrogen) and a very vital gas (oxygen).

Elements, Molecules and Compounds





Elements are the basic materials that make up
all matter.
An Element is a substance that can not be
chemically broken down and contains atoms of
only one variety.
All solids, liquids, and gases are made up of
Elements.
Some matter may be made up of only one
Element, but most matter is made up of more
than one Element.
There are 109 Elements, 92 of which are
natural. Millions of Compounds can be made
by combining different Elements.
Elements, Molecules and Compounds



When elements are combined, the properties of
the compound may differ considerably from that of
the individual elements.
Electrical properties of compounds are important
in water treatment, gas and oil refining, food
processing, chemical and pharmaceutical
manufacturing, medical applications, and
research.
Low voltage electricity is passed through the
compounds and used to take measurements that
provide information about the product being
tested.
Electron Flow
Electron Flow
Two theories – Conventional
Current Flow and Electron
Current Flow.
 Conventional Current –
current flows from positive to
negative.
 Conventional Current Flow
is used in electrical field and
by electrical engineers to aid
in explanation electrical circuit
properties.

Electron Flow
Electron Current Flow –
current flows from
negative to positive.
 Electron Current Flow is
used in electronic
semiconductor field to
assist in explaining the
operation of solid-state
electronic components.

Questions!?!?!?!?!