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Lecture 5.3 Aufbau Diagrams
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Aufbau Diagram Boxes Orbitals are hard to draw and the Aufbau Diagram is an easier way to show electron location, by using sets of boxes Each box can hold up to 2 e- s orbital – 1 box – total # of 2 e- p orbital-3 boxes –total # of 6e- d orbital-5 boxes – total # of 10 e- f orbital -7 boxes – total # of 14 e-
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Orbital Names of Elements in Principal Energy Level 1- 7 (Rows in the T)
2e- 6e- 10e- 14e- PEL 1: 1s PEL 2: 2s 2p PEL 3: 3s 3p 3d PEL 4: 4s 4p 4d 4f PEL 5: 5s 5p 5d 5f PEL 6: 6s 6p 6d 6f PEL 7: 7s 7p 7d 7f
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Filling the Aufbau Diagram
Electrons try to be as close to the protons in the nucleus Therefore lowest to energy levels close to the nucleus fill first Filling direction Always fill from bottom to top!!!
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e- filling Guidelines 1. Find AN of element = # e-
Example: Sodium AN= ___ = ____ e- 2. Start with 1s, 2s, 2p…. 3. Each box gets first 1 electon ↑, then when all suborbital have 1 e- per box, double up ↑↓ 4. Single unmatched arrow has to be ↑
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Practice the Aufbau Diagram for
Carbon Sodium Potassium
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Overlapping Orbitals Higher energy levels have overlapping orbitals
Example: 4s fills before 3d…. Means 4s is energetically lower than 3d!!!
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Set-up Aufbau Free-Hand
Draw x and y-axis Mark s, p, d, f section on x-axis Fill in s, p, d and f orbitals as lines (not boxes) – observe energy hierarchy of fold backs: 4s is energetically below 3d which is energeticall below 4p Fill with arrows as learned s: ___ p: ___ ___ ___ d: ___ ___ ___ ___ ___ f: ___ ___ ___ ___ ___ ___ ___
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Understanding the Atom
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Journal Draw a free-hand Aufbau diagram for Chromium
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Shorthand Electron Configurations
Translating the Aufbau diagram: Example: 2p5 PEL orbital # e- Means there are 5 e- in the 2p orbital
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Find the element 2p5 2s2 1s2 Shorthand: 1s2 2s2 2p5 add up 2+2+5=9 e-
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whi
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Finding and Interpreting Valence e-
The outermost orbital is called the Valence electron (Ve-)orbital Full Ve- orbital makes an element stable Ve- of NG= 8 Add xs2 + xp6 = 8 Ve-(octet) Ex: 1s2 2s2 2p6 3s2 3p3 = 5 Ve- of possible 8: element is unstable
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Valence electrons Ve- are involved in Rx
Ve- are involved in emission spectra Elements with half-filled Ve- orbitals are unstable and therefore react Noble gasses have full Ve- orbitals and are therefore stable and do not react
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[NG] shorthand e- Configuration
Noble gases: have full PEL Example: He: 1s2 Ne: Ar: Kr:
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[NG] e-shorthand Find the Noble gasses, use last Full shorthand: 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3 He Ne Ar [NG] shorthand: [Ar] 4s2 3d10 4p3
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Translate into [NG] e-shorthand Which element?
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For Aluminum draw____ Bohr’s Model Aufbau diagram Orbital Model
Electron shorthand [NG]shorthand
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Using the Periodic Table and for e-Configuration and Aufbau
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Practice Use the periodic Table to write the e-shorthand for H Ag Ge O
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Use your colored PT to write the full and [NG] shorthand for
Silver (Ag) Rutherfordium (Ru) Telurium (Te)
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d- block variations There is very little energy difference between 4s and 3d or 5s and 4d orbitals d-block elements move/exchange electrons among s and d-orbitals for greater stability Example Copper: Cu Cr Normally: [Ar] 4s2 3d9 [Ar] 4s2 3d4 more stable: [Ar] 4s13d10 [Ar] 4s13d5
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