1. 11.4 Electron Configuration
Period: 1
Group: 2

2. Electron Configuration Diagram
Electron Configuration: Electron arrangement.
Orbital/box diagram.
Opposing arrows = Opposing electron spins.
All 2p orbitals have the same energy.
There are 3 2p orbitals.

3. Electron Configuration Diagram Cont.
Q: How are opposite electron spins shown in box diagrams?
A: They are shown by opposing arrows

4. Classifying Electrons
Valence electrons- electrons at highest electron level [involved in bonding]
Core electron- inner most electrons [ not involved in bonding]
Atoms of elements in the same group have same # of electrons in a given type orbital.

5. Classifying Electrons Cont.
Q: Why are valence electrons important?
A: They are involved in bonding.

6. Wave-Mechanical Model and Valence-Electron Configuration
The model pictures electrons arranged in orbitals.
As the atoms build up the orbitals reoccur in going from one principal energy to another.
Elements with a particular type of valence configuration all show very similar chemical behavior.

7. Wave-Mechanical Model and Valence-Electron Configuration Cont.
Q: What do electrons with a particular type of valence configuration show?
A: Similar chemical behavior and bonding behavior.

8. Valence Electron Model

9. Atomic Properties & Sizes
Metals: lustrous appearance, malleable, conducts heat & electricity.
Non Metals: opposite of metals.
Sizes: atoms get larger as we go down a group and get smaller as we go from left to right across a period on a periodic table.

10. Atomic Properties & Sizes
Q: Describe metals.
A: They are lustrous, malleable and can conduct electricity very well.

11. More on Atomic Sizes
Atoms get bigger as electrons are added to larger principal energy levels.
The atom gets smaller as the electron cloud is drawn in by the increasing nuclear charge.

12. Ionization Energies
Ionization energy: The energy required to remove an electron from an individual atom in the gas phase.
Metals have relatively low ionization energies. Non-metals have relatively large energies.
[ More energy going up and right across a periodic table, and less energy going down and left across a p-table.]

13. Ionization Energy

14. Ionization Energy Q: Describe a metals ionization energy.
A: Metals have a relatively low ionization energy compared to that of a Non Metal.

15. Quiz How can you represent electron configuration?
What do elements in the same group have in common?
How does wave mechanical model picture electrons?
What are elements with metal and non-metal properties?
What makes the atom smaller?

16. Quiz Answers By using the orbital/box diagram.
Number of valence electrons.
It pictures electrons arranged in orbital.
Metalloids or semi-metals
The atom gets smaller as the electron cloud is drawn in by the increasing nuclear charge.

17. Links & References
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World of Chemistry – McDougal Littell