atomic structure. elements atoms components of an atom atomic number periodic table of elements...
TRANSCRIPT
Atomic Structure
• Elements• Atoms• Components of an Atom• Atomic Number• Periodic Table of Elements• Electrons• Electron Orbits
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?
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
• The electrons reside in the electron cloud
• The clouds are divided into 7 energy levels
• Electrons “reside” in lowest energy levels whenever possible.
ElectronsAreas 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 DiffusePrincipal Fundamental
ElectronsEnergy Level
Types of Orbitals
Maximum Electrons
1 1 (S)
2
2 2 (S & P)
8
3 3 (S, P, D)
18
4 4 (S, P, D & F)
32
5 4(S, P, D & F)
32
6 3(S, P, D)
18
7 2(S & P)
8
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
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:1s2s2p3s3p4s3d4p5s4d5p6s4f5d6p7s5f6d7p
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
1-3 valence electrons in outer orbit
Low Electronegativity
Good Conductors: Silver, Copper, Gold, Aluminum . . .
Electron flow is difficult between atoms
5-8 valence electrons in outer orbit
High Electronegativity
Examples: Mica, Glass, Rubber, Plastic . . .
Metals, Non-Metals, & Metalloids
Combination of metal and non-metal properties
Conduct heat & electricity better than insulators, but not as good as metals
Solids
Semi-conductors
Poor Conductors
Good Insulators
Dull Luster
Brittle
Low Density
Melt at lower temps
High Electronegativity
Good Conductors
Poor Insulators
Shiny
Malleable
High Density
Low 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