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# Electron Arrangement

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### Transcript

• 1. Electron Arrangement
• 2. Rutherford Model
While the Rutherford Model was an improvement over previous models, it still did not explain how the electrons were distributed around the nucleus.
What prevented the electrons from being pulled into the nucleus?
• 3. Bohr Model
Niels Bohr proposed that electrons can circle the nucleus only in allowed paths, or orbits.
Electrons in these orbits give the atoms a fixed energy.
Electrons are in the lowest energy state closest to the nucleus.
Orbits are separated by areas where electrons can’t exist.
Electron energy is higher when the electron is in orbits farther from the nucleus.
• 4. The Quantum Mechanical Model
Energy is quantized. It comes in chunks.
Quanta – the amount of energy needed to move from one energy level to another.
Quantum leap in energy
Schrödinger derives an equation that described the energy and position of the electrons in an atom.
• 5. A mathematical solution
It is not like anything you can see.
It does have energy levels for electrons
Orbits are not circular
It can only tell us the probability of finding an electron a certain distance from the nucleus.
The electron is found inside a blurry “electron cloud.”
• 6. Atomic Orbitals
Principal Quantum Number (n) = the energy level of the electron
Within each energy level the complex math of Schrödinger’s equation describes several shapes.
These are called atomic orbitals.
Regions where there is a high probability of finding an electron.
• 7. S Orbitals
1 s orbital for every energy level
Spherical shaped
Each s orbital can hold 2 electrons
Called the 1s, 2s, 3s, etc. orbitals
S Orbital
• 8. P Orbitals
Start at the second energy level
3 different directions
3 different shapes (dumbell)
Each can hold 2 electrons
P Orbital
• 9. D Orbitals
5 different shapes
Each can hold 2 electrons
D Orbital
• 10. F Orbitals
Start at the 4th energy level
Have seven different shapes
2 electrons per shape
F Orbital
• 11. Summary
• 12. By Energy Level
1st Energy Level
Only s orbital
Only 2 electrons
1s2
2nd Energy Level
s & p orbitals
2 in s, 6 in p
2s22p6
8 total electrons
• 13. Filling Order
Lowest energy fills first
The energy levels overlap
The orbitals do not fill up order of energy level
Counting system
Each “___” is an orbital shape
Room for 2 electrons
• 14. 7s 7p
__ __ __ __
6s 6p 6d
__ __ __ __ __ __ __ __ __
5s 5p 5d 5f
__ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
4s 4p 4d 4f
__ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __
3s 3p 3d
__ __ __ __ __ __ __ __ __
2s 2p
__ __ __ __
1s
__
Increasing Energy
• 15. Electron Configurations
The way electrons are arranged in atoms
Aufbau principle – electrons enter the lowest energy level first
This causes difficulties because of the overall of orbitals of different energies
Paulie Exclusion Principle – at most 2 electrons per orbital – different spins
Hund’s Rule – when electrons occupy orbital of equal energy, they don’t pair up until they have to
• 16. Practice
Phosphorus
How many electrons??
Account for 15
• 17. 7f __ __ __ __ __ __ __
7d __ __ __ __ __
6f __ __ __ __ __ __ __
7p __ __ __
6d __ __ __ __ __
5f __ __ __ __ __ __ __
7s __
6p __ __ __
5d __ __ __ __ __
4f __ __ __ __ __ __ __
6s __
5p __ __ __
4d __ __ __ __ __
5s __
4p __ __ __
3d __ __ __ __ __
4s __
3p __ __ __
3s __
2p __ __ __
2s __
1s __
Filling Order
• 18. Orbital Notation for Phosphorous
• 19. A trick…
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
1s2
2 electrons
• 20. A trick…
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
1s22s2
4 electrons
• 21. A trick…
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
1s22s22p63s2
12 electrons
• 22. A trick…
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
1s22s22p63s23p64s2
20 electrons
• 23. A trick…
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
1s22s22p63s23p64s23d104p65s2
38 electrons
• 24. A trick…
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
1s22s22p63s23p64s23d104p65s24d105p66s2
56 electrons
• 25. A trick…
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
1s22s22p63s23p64s23d104p65s24d105p66s24f14
5d106p67s2
88 electrons
• 26. A trick…
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
1s22s22p63s23p64s23d104p65s24d105p66s24f14
5d106p67s25f146d107p6
118 electrons
• 27. A trick…
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
1s22s22p63s23p64s23d104p65s24d105p66s24f14
5d106p67s25f146d107p66f147d10
142 electrons
• 28. A trick…
7s 7p 7d 7f
6s 6p 6d 6f
5s 5p 5d 5f
4s 4p 4d 4f
3s 3p 3d
2s 2p
1s
1s22s22p63s23p64s23d104p6
5s24d105p66s24f145d106p67s25f146d107p66f147d107f14
156 electrons
Aufbau Principle
• 29. Rewrite when done..
1s22s22p63s23p64s23d104p65s24d105p66s2
4f145d106p67s25f146d107p66f147d107f14
Group the energy levels together
1s22s22p63s23p63d104s24p64d104f145s25p65d105f146s26p66d106f147s27p67d107f14
• 30. Exceptions to Electron Configurations
• 31. Orbitals fill in order…
Lowest energy to higher energy
Adding electrons can change the energy of the orbital
Filled and half-filled orbitals have a lower energy
Makes them more stable
Changes the filling order of d orbitals
• 32. Practice
1s22s22p63s23p63d34s2
Titanium
1s22s22p63s23p63d24s2
Chromium
(expected)1s22s22p63s23p63d44s2
(correct) 1s22s22p63s23p63d54s1
Why? It more stable – gives us two half-filled orbitals!
• 33. Exceptions
Same principle applies to Copper!
Remember these exceptions:
d4s2 d5s1
d9s2  d10s1
• 34. Electrons on the Periodic Table
• 35. Table 3(p. 116)
Notice that as you move across the periodic table, the elements increase in the number of electrons.
Notice the electron-configuration notation  Aufbau Principle
• 36. Noble Gas Notation
The elements all the way to the right of the periodic table make up Group 18.
Their sublevels are completely filled, and they are said to have an octet of electrons.
These elements (helium, neon, argon, krypton, xenon, and radon) are called Noble Gases.
We can use their electron configurations to simplify the electron configurations we write for other elements!
• 37. Example
Neon
Ne = 1s22s22p6
Sodium
Na = [Ne]3s1
Tables 4 - 6 (pp. 117-120)
Noble-Gas Configuration
Refers to an outer main energy level occupied, in most cases, by eight electrons.