1. Atomic Structures
Magic of Electrons
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2. Atomic Structure Elements Atoms Components of an Atom Atomic Number
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Atomic Structure
Elements
Atoms
Components of an Atom
Atomic Number
Periodic Table of Elements
Electrons
Electron Orbits

3. Elements The simplest form of matter Atomic Structure PLTW Gateway®
Unit 4 – Lesson 4.1 – What is Electricity?
Elements
The simplest form of matter
Matter is the material from which all known physical objects are made.
The image is of Beryllium, which has an atomic number of 4.

4. Atomic Structure
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Unit 4 – Lesson 4.1 – What is Electricity?
Atoms
The smallest piece of an element that contains all properties of that element

5. Components of an Atom Nucleus
Atomic Structure
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Components of an Atom
Nucleus
The center portion of an atom containing the protons and neutrons
Protons
Positively charged atomic particles (shown in red)
Neutrons
Uncharged atomic particles (shown in blue)

6. Atomic Number How many protons are in this nucleus?
Atomic Structure
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Unit 4 – Lesson 4.1 – What is Electricity?
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?

7. Periodic Table of Elements
Atomic Structure
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Periodic Table of Elements
NASA
Which element has 4 protons?

8. For this unit, we mainly care about electrons in atoms.
Atomic Structure
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Unit 4 – Lesson 4.1 – What is Electricity?
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.

9. Electrons Negatively charged particles Atomic Structure PLTW Gateway®
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Electrons
Negatively charged particles

10. Electrons 3D 2D Models of the Atom Bohr’s Model Atomic Structure
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Electrons
Models of the Atom 3D 2D
Bohr’s Model

11. Electrons The electrons reside in the electron cloud
Atomic Structure
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Electrons
The electrons reside in the electron cloud
The clouds are divided into 7 energy levels
Electrons “reside” in lowest energy levels whenever possible.
Apartment Building Analogy
The electron cloud is like an apartment building without an elevator. There are seven stories (energy levels). People will want to live on the lowest floor of the apartment building because it’s easier. The same is true with Electrons: they will want to “live” on the lowest energy level, because it is easier.

12. Atomic Structure
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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
Apartment Analogy
Each apartment building has different types of apartments; studio apartments holding one or two people, one bedroom apartments which hold more people, two bedroom apartments which hold more than one bedroom apartments, and maybe even three bedroom apartments which hold the most. The same concept applies with electrons.
Apartment: Each floor of the apartment building has different types of apartments where people live.
Electrons: Each energy level has different types of orbitals where the electrons live.
Sharp
Principal
Diffuse
Fundamental

13. Electrons Types of Orbitals S orbitals can hold up to 2 electrons
Atomic Structure
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Electrons
Energy Level
Types of Orbitals
Maximum Electrons 1
(S) 2
(S & P) 8 3
(S, P, D) 18 4
(S, P, D & F) 32 5 6 7
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
Apartment Analogy
Each floor of the apartment may have different types of apartments. Therefore, each floor of the apartment may hold different numbers of people.
Each energy level of an atom may hold different numbers of electrons in its different types of orbitals.

14. Orbital Filling order:
Atomic Structure
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Electrons
Orbital Filling order: 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p
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
Apartment Analogy
People may move to a higher floor before lower floors become full.
Electrons may “move” to a higher energy level before the lower levels are entirely full. Because of this there can never be more than 8 electrons in the highest energy level. Why???? This is a question best answered by college level chemistry and/or physics and beyond the scope of this course.

15. Atomic Structure
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Unit 4 – Lesson 4.1 – What is Electricity?
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
It is easier for the copper atom to let go of one electron than it is to pick up 7 electrons to be full

16. Atomic Structure
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Unit 4 – Lesson 4.1 – What is Electricity?
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.
It is easier for the sulfur atom to pick up 2 electrons to be full, than to get rid of 6 electrons to be empty.

17. What does all this have to do with Electricity?
Atomic Structure
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Unit 4 – Lesson 4.1 – What is Electricity?
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.

18. Conductors and Insulators
Electricity
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Unit 4 – Lesson 4.1 – What is Electricity?
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 . . .
Many examples of insulators are materials because atoms of one element have already bonded with atoms from other elements to make the materials very stable.

19. Conductors and Insulators
Electricity
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Unit 4 – Lesson 4.1 – What is Electricity?
Conductors and Insulators
Identify conductors and insulators
Insulators
Conductors

20. Metals, Non-Metals, & Metalloids
Electricity
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Metals, Non-Metals, & Metalloids

21. Metals, Non-Metals, & Metalloids
Electricity
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Metals, Non-Metals, & Metalloids
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
Malleable – the ability to be shaped.
Metals are generally good conductors because they have 1 or 2 valance electrons.
Non-metals are good insulators because they have 5 or more valence electrons.
Combination of metal and non-metal properties
Conduct heat & electricity better than insulators, but not as good as metals
Solids
Semi-conductors

22. Semiconductors Include Carbon, Germanium, and Silicon
Electricity
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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
Transistors and microchips are the heart of electronic devices.
Doping is the process of adding impurities to increase conductivity.
***See the Teacher Notes for instructions on how to do a demonstration of doping.

23. Electron Flow in Conductors
Atomic Structure
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Electron Flow in Conductors
An atom will lose a valence electron when “pushed” by an electron from another atom.
Conductors will easily lose electrons. The electrons can be knocked out of an atom into the next if enough force is applied.

24. Electricity
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Unit 4 – Lesson 4.1 – What is Electricity?
Electron Flow
Electricity is created as electrons collide and transfer from atom to atom.
Play Animation

25. Atomic Structure
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Unit 4 – Lesson 4.1 – What is Electricity?
Image Resources
Microsoft, Inc. (2008). Clip Art. Retrieved September 10, 2008, from
National Aeronautics and Space Administration (NASA). (n.d.). Genesis: Search for origins. Retrieved September 10, 2008, from