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Modern Atomic Theory How do electrons create the chemical trends on the Periodic Table
Wave-Mechanical Model Assumptions <ul><li>We never know exactly how electrons move in an atom </li></ul><ul><li>At any poi...
Wave-Mechanical Model Assumptions (cont) <ul><li>We call the probability maps orbitals </li></ul><ul><ul><li>An orbital is...
Wave-Mechanical Model Assumptions (cont) <ul><li>The “edge” of the orbital is fuzzy, like the outer edge of the earth’s at...
Three Rules for electron orbital filling <ul><li>Aufbau Principle </li></ul><ul><li>Pauli Exclusion Principle </li></ul><u...
Principal Components of the Wave-Mechanical Model <ul><li>Atoms have a series of energy levels called Principal Energy Lev...
Principal Components cont <ul><li>The energy level increases as the value of n increases </li></ul><ul><li>Each Energy Lev...
Principal Components cont <ul><li>The number of the energy level, and the letter of the sub-level (orbital shape) are used...
Principal Components cont <ul><li>The shape of the orbital indicates 90% electron probability </li></ul><ul><ul><li>-NOT t...
Energy Levels <ul><li>Electrons fill the orbitals in order of energy, from lowest energy to highest </li></ul><ul><li>The ...
What this means is…. <ul><li>3d has a higher energy than 4s </li></ul><ul><li>Even though 3d is closer to the nucleus as f...
This creates a pattern on the Periodic Table <ul><li>Explains the trends seen in much of the chemical behavior of the elem...
Electron Configuration Patterns
The whole Periodic Table
 
Short Form Electron Configuration <ul><li>The electron configuration for Sr is </li></ul><ul><li>1s 2 2s 2 2p 6 3s 2 3p 6 ...
Short Form Cont <ul><li>We can shorten the electron configuration for Sr by writing the electron configuration for Kr as [...
To write the short form: <ul><li>Take the electron configuration for the noble gas on the period above the element you are...
Valence Electrons <ul><li>Valence Electrons are the electrons in the outermost energy level of an atom </li></ul><ul><li>T...
Valence Electrons <ul><li>Are the most important electrons to chemists </li></ul><ul><li>Being the outermost electrons, th...
Valence Electrons of Groups <ul><li>Note that the atoms in the same vertical groups on the periodic table have the same nu...
Valence electron configurations <ul><li>For Chlorine </li></ul><ul><li>Electron Configuration: </li></ul><ul><li>[Ne]3s 2 ...
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Minooka -Atomic Theory

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Minooka -Atomic Theory

  1. 1. Modern Atomic Theory How do electrons create the chemical trends on the Periodic Table
  2. 2. Wave-Mechanical Model Assumptions <ul><li>We never know exactly how electrons move in an atom </li></ul><ul><li>At any point in time there are areas around the nucleus where the electron is more likely to be (higher electron probability) </li></ul><ul><li>We can make a probability map of where the electron is more likely to be </li></ul><ul><ul><li>The more intense the color on the map, the more likely the electron will be there </li></ul></ul>
  3. 3. Wave-Mechanical Model Assumptions (cont) <ul><li>We call the probability maps orbitals </li></ul><ul><ul><li>An orbital is the three dimensional space around the nucleus where electron probability is high </li></ul></ul>
  4. 4. Wave-Mechanical Model Assumptions (cont) <ul><li>The “edge” of the orbital is fuzzy, like the outer edge of the earth’s atmosphere </li></ul><ul><li>Chemists and physicists arbitrarily define the orbital as containing 90% electron probability </li></ul>
  5. 5. Three Rules for electron orbital filling <ul><li>Aufbau Principle </li></ul><ul><li>Pauli Exclusion Principle </li></ul><ul><li>Hund’s Rule </li></ul><ul><ul><li>When electrons occupy orbitals of equal energy, one electron enters each orbital until all of the orbitals contain one electron with parallel spins </li></ul></ul><ul><ul><li>Then the second electron enters the orbitals with opposite spins </li></ul></ul>
  6. 6. Principal Components of the Wave-Mechanical Model <ul><li>Atoms have a series of energy levels called Principal Energy Levels </li></ul><ul><ul><li>A. Designated by whole numbers </li></ul></ul><ul><ul><li>B. Symbolized by n </li></ul></ul><ul><ul><ul><li>- n=1, n=2, n=3, n=4 </li></ul></ul></ul>
  7. 7. Principal Components cont <ul><li>The energy level increases as the value of n increases </li></ul><ul><li>Each Energy Level contains one or more types of orbitals called sub-levels </li></ul><ul><li>The number of sub-levels (or types of orbitals) equals n (number of the energy level) </li></ul>
  8. 8. Principal Components cont <ul><li>The number of the energy level, and the letter of the sub-level (orbital shape) are used to designate the energy level, sub-level, and orbital shape (I.e. 1s, 2p) </li></ul><ul><li>An orbital can be empty or it can contain up to two electrons as long as they have opposite spins </li></ul>
  9. 9. Principal Components cont <ul><li>The shape of the orbital indicates 90% electron probability </li></ul><ul><ul><li>-NOT the details of the electron’s movement </li></ul></ul>
  10. 10. Energy Levels <ul><li>Electrons fill the orbitals in order of energy, from lowest energy to highest </li></ul><ul><li>The order of energy is: </li></ul><ul><li>1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p </li></ul>
  11. 11. What this means is…. <ul><li>3d has a higher energy than 4s </li></ul><ul><li>Even though 3d is closer to the nucleus as far as the number of the energy level </li></ul><ul><li>Electrons will fill 4s before 3d </li></ul><ul><li>4s is still the outer orbital compared to 3d </li></ul><ul><li>It is not Mrs. Erfft’s fault </li></ul><ul><li>Mrs. Erfft is not confused </li></ul>
  12. 12. This creates a pattern on the Periodic Table <ul><li>Explains the trends seen in much of the chemical behavior of the elements </li></ul>
  13. 13. Electron Configuration Patterns
  14. 14. The whole Periodic Table
  15. 16. Short Form Electron Configuration <ul><li>The electron configuration for Sr is </li></ul><ul><li>1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 </li></ul><ul><li>The electron configuration for Kr is1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 </li></ul><ul><li>Note that everything is the same through the fourth energy level (4p 6 is complete) </li></ul>
  16. 17. Short Form Cont <ul><li>We can shorten the electron configuration for Sr by writing the electron configuration for Kr as [Kr] </li></ul><ul><li>1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 =[Kr] </li></ul><ul><li>Then we can write the configuration for Sr as [Kr]5s 2 </li></ul>
  17. 18. To write the short form: <ul><li>Take the electron configuration for the noble gas on the period above the element you are focusing on </li></ul><ul><li>Shorten the electron configuration of the noble gas by putting the symbol of the noble gas into brackets </li></ul><ul><li>Write the rest of the electron configuration to the right of the bracketed noble gas symbol in the correct order </li></ul>
  18. 19. Valence Electrons <ul><li>Valence Electrons are the electrons in the outermost energy level of an atom </li></ul><ul><li>These are the electrons in the s and p orbitals specifically </li></ul><ul><li>All of the other electrons are called the core electrons </li></ul>
  19. 20. Valence Electrons <ul><li>Are the most important electrons to chemists </li></ul><ul><li>Being the outermost electrons, they are the electrons that govern the chemical behavior of the element/atom </li></ul><ul><li>Valence electrons are the electrons that form bonds and are lost or gained to form ions </li></ul>
  20. 21. Valence Electrons of Groups <ul><li>Note that the atoms in the same vertical groups on the periodic table have the same numbers of electrons in the same orbitals </li></ul><ul><li>Just higher energy levels as you go down a column </li></ul><ul><li>Therefore elements in the same groups show the same valence electron configuration </li></ul>
  21. 22. Valence electron configurations <ul><li>For Chlorine </li></ul><ul><li>Electron Configuration: </li></ul><ul><li>[Ne]3s 2 3p 5 </li></ul><ul><li>Valence Configuration: 3s 2 3p 5 </li></ul>

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