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1 DC ELECTRICAL CIRCUITS ATOMIC THEORY
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DC ELECTRICAL CIRCUITS
ATOMIC THEORY
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Objectives:
List the three major parts of an atom.
State the law of charges.
Discuss the law of centrifugal force.
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Electrical sources are divided into two basic types:
Direct Current (DC) which is unidirectional (one way.)
Alternating Current (AC) which is bidirectional (two way, or back and forth.)
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TO UNDERSTAND ELECTRICITY WE FIRST HAVE TO START WITH:
MATTER
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WHAT IS MATTER?
Matter is anything that occupies space and has weight.
Matter is either an element or a compound.
The atom is the basic building block of the universe.
An element is the basic building block of nature.
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An element is composed of only one type of atom.
An element is a substance that can not be reduced to a simpler substance by chemical means.
There are 103 elements, all listed on the periodic table of elements.
HYDROGEN ATOM
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The Bohr model of an atom shows the orbiting electrons around a nucleus of protons and neutrons.
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A molecule is the result of the joining of two or more different types of atoms.
A molecule is the chemical combination of two or more atoms.
Its the smallest physical unit of an element or compound, consisting of one or more like atoms in an element and two or more different atoms in a compound.
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The chemical combination of two or more elements is called a compound.
A compound can be separated by a chemical means but not by a physical means.
An example of a compound is water, H20, a combination of two elements.
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THE ATOM:The smallest part of an element that retains the characteristics of the element.
Contains charged particles called ions.
Two types of ions:
POSITIVE NEGATIVE
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THE 3 PRINCIPAL PARTS OF AN ATOM:
Positively charged particles called PROTONS
Negatively charged particles calledELECTRONS
Uncharged particles calledNEUTRONS
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Electrons have a negative charge and orbit the nucleus.
Protons have a positive charge and are contained in the nucleus.
Neutrons have no charge and combine with the protons to form the nucleus.
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The number of protons in the nucleus is called the elements atomic number, the atomic number distinguishes one element from another.
THIS ATOM HAS 7 PROTONS IN THE NUCLEUS, FROM THE PERIODIC TABLE OF ELEMENTS IT IS LISTED AS NITROGEN.
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Each element also has an atomic weight, the atomic weight is the mass of the atom.
The atomic weight is the total number of protons and neutrons in the nucleus.
COPPER Cu
ATOMIC WEIGHT 63.546STATE SOLIDELECTRONS 29PROTONS 29ELECTRON SHELLS 2, 8, 18, 1
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PROTONS HAVE A POSITIVE CHARGE.
ELECTRONS HAVE A NEGATIVE CHARGE.
THE LAW OF ELECTRICAL CHARGE
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The Law of Charges:
Opposite charges attract!
The Law of Charges:
Opposite charges attract!
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The Law of Charges:
Like charges repel!
The Law of Charges:
Like charges repel!
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Centrifugal Force: Keeps electrons
from crashing into the nucleus.
Centrifugal Force: Keeps electrons
from crashing into the nucleus.
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Centrifugal force along with the laws of attraction combine to keep the electron orbiting the nucleus (protons) at very high speeds, this force is called electrostatic force.
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The electrons orbit around the nucleus.
Each orbit is called a shell.
The outer most orbit or shell is called the valence shell.
The number of electrons contained in the valence shell is the atoms valence.
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