Atomic Structure
Atomic Structure
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Elements
Atoms
Components of an Atom
Atomic Number
Periodic Table of Elements
Electrons
Electron Orbits
Elements
The simplest form of matter
Atoms
The smallest piece
of an element that
contains all
properties of that
element
Components of an Atom
Nucleus
The center portion of
an atom containing the
protons and neutrons
Protons
Positively charged
atomic particles
Neutrons
Uncharged atomic
particles
Atomic Number
The atomic number is
equal to the number of
protons in the nucleus
of an atom.
The atomic number
identifies the element.
How many protons
are in this nucleus?
Periodic Table of Elements
NASA
Which element has 4 protons?
Electrons
For this unit, we mainly care about
electrons in atoms.
Why?
It is important to understand the
“how and why” of the movement of
electrons to understand electricity.
Electrons
Negatively charged
particles
Electrons
Models of the Atom
3D
Bohr’s Model
2D
Electrons
•The electrons reside in the
electron cloud
•The clouds are divided into 7
energy levels
•Electrons “reside” in lowest
energy levels whenever
possible.
Electrons
Areas within each energy level where electrons
move around the nucleus of an atom are known
as Electron Orbitals.
There are four different type of orbitals, each type
able to contain different numbers of electrons
Sharp
Principal
Diffuse
Fundamental
Electrons
Energy
Level
Types of Orbitals
S orbitals can hold up to
2 electrons
P orbitals can hold up to
6 electrons
D orbitals can hold up to
10 electrons
F orbitals can hold up to
14 electrons
1
Types of Maximum
Orbitals Electrons
1
2
(S)
2
2
8
(S & P)
3
3
18
(S, P, D)
4
4
32
(S, P, D & F)
5
4
32
(S, P, D & F)
6
3
18
(S, P, D)
7
2
(S & P)
8
Electrons
Electrons will not completely fill
all the orbitals in an energy level
before moving up to another
level. Because of this,
There are never more than 8
electrons in the highest energy
level!
The electrons in the highest
energy level of an atom are
called the Valence Electrons
Orbital Filling order:
1s
2s
2p
3s
3p
4s
3d
4p
5s
4d
5p
6s
4f
5d
6p
7s
5f
6d
7p
Electron Orbits
Atoms work to have their valence level
either filled (8) or empty(0) of electrons.
How many electrons
are in the valence
level?
1
Copper has a loose
hold on this
electron, so it can
easily be moved
Electron Orbits
Atoms like to have their valence level either
filled (8) or empty(0) of electrons.
How many electrons
are in the valence
level?
6
Sulfur has space to
gain two electrons in
its valence level.
What does all this have to do
with Electricity?
The number of valence electrons in an atom
will determine if an element will allow
electricity to flow.
The ability of an atom to draw electrons to
itself (away from its neighbors) is called
Electronegativity.
Conductors and Insulators
Conductors
Insulators
Electrons flow easily
between atoms
Electron flow is difficult
between atoms
1-3 valence electrons in
outer orbit
5-8 valence electrons in
outer orbit
Low Electronegativity
High Electronegativity
Good Conductors:
Silver, Copper, Gold,
Aluminum . . .
Examples: Mica, Glass,
Rubber, Plastic . . .
Conductors and Insulators
Identify conductors and insulators
Conductors
Insulators
Metals, Non-Metals, & Metalloids
Metals, Non-Metals, & Metalloids
Good Conductors
Poor Conductors
Poor Insulators
Good Insulators
Shiny
Dull Luster
Brittle
Malleable
Combination of metal and non-metal properties
Low Density
High Density
Conduct heat & electricity better than insulators, but not
Melt at lower temps
as Electronegativity
good as metals
Low
Solids
Semi-conductors
High
Electronegativity
Semiconductors
•Include Carbon, Germanium, and Silicon
•Contain 4 valence electrons
•Neither a good insulator, nor a good
conductor, but can be made a better
conductor through doping.
•Needed for transistors and microchips
•Silicon is most often used in electronic
applications
•Silicon is an insulator at room temperature
but becomes a conductor when heated
Electron Flow in Conductors
An atom will lose a valence electron when
“pushed” by an electron from another
atom.
Electron Flow
Electricity is created as electrons collide and
transfer from atom to atom.
Play Animation
Image Resources
Microsoft, Inc. (2008). Clip Art. Retrieved September 10, 2008, from
http://office.microsoft.com/en-us/clipart/default.aspx
National Aeronautics and Space Administration (NASA). (n.d.).
Genesis: Search for origins. Retrieved September 10, 2008, from
http://genesismission.jpl.nasa.gov/educate/scimodule/cosmic/ptable.
html