1. Energy Unit
Electrons in Orbitals

2. 1. Atom has small positive nucleus.
Bohr’s Atomic Model
1. Atom has small positive nucleus.
Good start but some basic problems:
2. Electrons orbit like planets orbit the sun.
Electrons do not “orbit” in circular paths.
3. Electrons orbit in certain allowed energy levels.
Could not explain why negative electrons didn’t get attracted into the nucleus
4. Electrons can jump to different orbits but only by absorbing or emitting a photon of light with the correct energy content.
This model only worked for Hydrogen
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3. Schrodinger Wave Equation
Equation for probability of a single electron being found along a single axis (x-axis).
Erwin Schrodinger

4. Heisenberg Uncertainty Principle
“One cannot simultaneously determine both the position and momentum of an electron.”
You can find out where the electron is, but not where it is going.
OR…
You can find out where the electron is going, but not where it is!
Werner
Heisenberg

5. Wave Mechanical Model Electron states are described as orbitals.
An orbital is described as the probability map of an electron’s motion.

6. Orbitals vs. Orbits Orbitals are nothing like orbits.
An orbit is a defined path
An orbital is a probability map.
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7. These are based on the distance from the nucleus.
Electron Energy Levels (Shells)
These are based on the distance from the nucleus.

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9. Principle Energy Levels
Discrete Energy levels that are labeled with integers.
1, 2, 3, 4, 5, 6, 7
Sublevels
Each Principle Energy Level is subdivided into sublevels and labeled with a letter.
The letters tell the shape of the orbital.
s (holds 2 e- )
p (holds 6 e- )
d (holds 10 e- )
f (holds 14 e- )
Each orbital can hold 2 electrons.

10. Energy Levels, Sublevels, Electrons
Sublevels in
main energy
level
(n sublevels)
Number of
orbitals per
sublevel
Electrons
per sublevel
electrons per
level (2n2) 1 s 2 p 3 6 8 d 5 10 18
4,5,6,7 f 7 14 32

11. Shapes of Sublevels
S sublevels are “spherical” in shape and have only 1 orbital.
The S sublevel can hold a maximum of 2 electrons.
Every energy level has an s sublevel.
The only difference being the diameter!
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12. The p sublevels are dumbbell shaped and are made of 3 orbitals or “lobes”.
The p sublevel can hold a maximum of 6 electrons.
p sublevels are found on energy levels 2 or greater
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13. d sublevels are found on energy levels 3 or greater
The d sublevels are four-petaled and are made of 5 orbitals or “lobes”.
The d sublevel can hold a maximum of 10 electrons.
d sublevels are found on energy levels 3 or greater
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14. The f sublevels are made of 7 orbitals or “lobes”.
The f sublevel can hold a maximum of 14 electrons.
f sublevels are found on energy levels 4 or greater
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15. Orbital filling table

17. Pauli Exclusion Principle
No more than two electrons may occupy the same orbital and they must have opposite spins
Wolfgang
Pauli

18. Hund’s Rule
The most stable arrangement of electrons is one with the maximum number of unpaired electrons.
It minimizes electron-electron repulsions and stabilizes the atom.
Electrons find each other very repulsive, so they too, are in a lower energy state if each “gets their own room” or in this case orbital.

19. Orbital Diagram for A Fluorine Atom
1s 2s p s     

20. Orbital Diagram for A Nitrogen Atom
1s 2s p s     

21. Orbital Diagram

23. Element Configuration notation Orbital notation Noble gas
Lithium
1s22s1
____ ____ ____ ____ ____
1s s p
[He]2s1
Beryllium
1s22s2
[He]2s2
Boron
1s22s2p1
[He]2s2p1
Carbon
1s22s2p2
[He]2s2p2
Nitrogen
1s22s2p3
1s s p
[He]2s2p3
Oxygen
1s22s2p4
[He]2s2p4
Fluorine
1s22s2p5
[He]2s2p5
Neon
1s22s2p6
[He]2s2p6