Electron configuration

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Electron configuration

  1. 1. Electron Configuration
  2. 2. <ul><li>Electron configurations tells us in which orbitals the electrons for an element are located. </li></ul><ul><li>Three rules: </li></ul><ul><ul><li>electrons fill orbitals starting with lowest n and moving upwards(Aufbau); </li></ul></ul><ul><ul><li>no two electrons can fill one orbital with the same spin (Pauli); </li></ul></ul><ul><ul><li>electrons fill each orbital singly before any orbital gets a second electron (Hund’s rule). </li></ul></ul>Electron Configurations
  3. 3. Filling order Diagram <ul><li>Aufbau Principle </li></ul>
  4. 4. Electron Configurations <ul><li>The electron configuration of an atom is a shorthand method of writing the location of electrons in the atom. </li></ul><ul><li>The level and sublevel is written followed by a superscript with the number of electrons . </li></ul>
  5. 5. Writing Electron Configurations <ul><li>First, determine how many electrons are in the atom. Iron has Z = 26 . </li></ul><ul><li>Follow the Aufbau filling order diagram: </li></ul><ul><ul><ul><ul><li>Fe: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 4 s 2 3 d 6 </li></ul></ul></ul></ul><ul><li>The sum of the superscripts equals the atomic number of iron (26) </li></ul>
  6. 6. ORBITAL DIAGRAM
  7. 7. Practice Which is the correct electron configuration for the element titanium (Ti, atomic number 22)? What element has the electron configuration notation 1s 2 2s 2 2p 6 3s 1 ? Which is the correct orbital notation for the element aluminum (Al, atomic #13)? The following orbital diagram is for the element ______________.
  8. 8. Electron Configurations and the Periodic Table
  9. 9. We can use the periodic table to predict the level and sublevel of an element.
  10. 10. BLOCKS
  11. 11. Noble Gas Electron Configurations <ul><li>Recall, the electron configuration for Na is: </li></ul><ul><ul><li>Na: 1 s 2 2 s 2 2 p 6 3 s 1 </li></ul></ul><ul><li>We can abbreviate the electron configuration by indicating the innermost electrons with the symbol of the preceding noble gas. </li></ul><ul><li>The preceding noble gas with an atomic number less than sodium is neon, Ne. We rewrite the electron configuration: </li></ul><ul><ul><li>Na: [Ne] 3 s 1 </li></ul></ul>
  12. 12. NOBLE GAS CONFIGURATION The electron configuration for gold (Au) is: 1s 2  2s 2  2p 6  3s 2  3p 6  4s 2  3d 10  4p 6  5s 2  4d 10  5p 6 6s 2  4f 14  5d 9 Gold (Au) is in the 6 th row of the periodic table : This gives us: [Xe] 6s 2  4f 14  5d 9
  13. 13. Noble gas notation
  14. 14. MORE EXAMPLES Noble Gas Notation:  C = [He]2s 2 2p 2     Te = [Kr]5s 2 4d 10 5p 4 I = [Kr]5s 2 4d 10 5p 5
  15. 15. Valence Electrons <ul><li>When an atom undergoes a chemical reaction, only the outermost electrons are involved. </li></ul><ul><li>These electrons are of the highest energy and are furthest away from the nucleus. These are called the valence electrons . </li></ul>
  16. 16. Predicting Valence Electrons <ul><li>The GROUP indicates the number of valence electrons. </li></ul><ul><ul><li>Group 1 elements have 1 valence electron </li></ul></ul><ul><ul><li>Group 2 elements have 2 valence electrons </li></ul></ul><ul><ul><li>Group 13 elements have 3 valence electrons </li></ul></ul><ul><ul><li>Group 14 elements have 4 valence electrons </li></ul></ul><ul><ul><li>Group 15 elements have __? _valence electrons </li></ul></ul><ul><ul><li>- Group 16 elements have ? valence electrons </li></ul></ul>
  17. 17. Electron Dot Formulas <ul><li>An electron dot formula of an elements shows the symbol of the element surrounded by its valence electrons. </li></ul><ul><li>We use one dot for each valence electron. </li></ul><ul><li>Consider phosphorous, P, which has 5 valence electrons. Here is the method for writing the electron dot formula. </li></ul>
  18. 18. Ions and its charge <ul><li>Recall, that atoms lose or gain electrons to form ions. </li></ul><ul><li>The charge of an ion is related to the number of valence electrons on the atom. </li></ul><ul><li>Group IA/1 metals lose their one valence electron to form 1+ ions. </li></ul><ul><ul><li>Na -> Na + (lost 1 electron) </li></ul></ul><ul><li>Metals lose their valence electrons to form ions. </li></ul>
  19. 19. Predicting Ionic Charge <ul><li>Group IA/1 metals form 1+ ions, group IIA/2 metals form 2+ ions, group IIIA/13 metals form 3+ ions, and group IVA/14 metals from 4+ ions. </li></ul><ul><li>By losing their valence electrons, they achieve a noble gas configuration. </li></ul><ul><li>Similarly, nonmetals can gain electrons to achieve a noble gas configuration. </li></ul><ul><li>Group VA/15 elements form -3 ions, group VIA/16 elements form -2 ions, and group VIIA/17 elements form -1 ions. </li></ul>
  20. 20. Ion Electron Configurations <ul><li>When we write the electron configuration of a positive ion, we remove one electron for each positive charge: </li></ul><ul><ul><li> Na -> Na + </li></ul></ul><ul><ul><li>1 s 2 2 s 2 2 p 6 3 s 1 -> 1 s 2 2 s 2 2 p 6 </li></ul></ul><ul><li>When we write the electron configuration of a negative ion, we add one electron for each negative charge: </li></ul><ul><ul><li> O -> O 2- </li></ul></ul><ul><ul><li> 1 s 2 2 s 2 2 p 4 -> 1 s 2 2 s 2 2 p 6 </li></ul></ul>
  21. 21. Predicting charges <ul><li>We can predict the charge on the ion of an element from its position on the periodic table. </li></ul>

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