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Quick intro to chemistry

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  1. 1. Chemistry Bonding
  2. 2. Electron energy levels <ul><li>Electrons travel around the nucleus in energy levels </li></ul><ul><li>Each level has a limited capacity for electrons </li></ul><ul><li>1 st : 2 electrons </li></ul><ul><li>2 nd : 8 electrons </li></ul><ul><li>3 rd : 8 electrons </li></ul>
  3. 3. Energy Levels Cont <ul><li>Atoms are most stable “Happiest” when their outer energy levels is full of electrons </li></ul>
  4. 4. Ions <ul><li>An atom that has gained or lost an electron </li></ul><ul><ul><li>Negative Ion </li></ul></ul><ul><ul><ul><li>Gained an electron </li></ul></ul></ul><ul><ul><li>Positive Ion </li></ul></ul><ul><ul><ul><li>Lost an electron </li></ul></ul></ul><ul><li>***ELECTRONS HAVE A NEGATIVE CHARGE*** </li></ul>
  5. 5. Isotopes <ul><li>Atoms of the same element that have a different # of neutrons </li></ul><ul><ul><li>Example: Carbon </li></ul></ul><ul><ul><ul><li>Usually has 6 neutrons </li></ul></ul></ul><ul><ul><ul><li>Sometimes has 7 or 8 </li></ul></ul></ul><ul><ul><ul><li>Known as Carbon-12, or Carbon-13, or Carbon-14 </li></ul></ul></ul><ul><ul><li>Useful in science, used to date fossils </li></ul></ul>
  6. 6. Physical Reaction <ul><li>Where shape is changed </li></ul><ul><ul><li>Liquid to solid </li></ul></ul><ul><ul><li>Liquid to gas </li></ul></ul><ul><ul><li>Crumpling paper </li></ul></ul><ul><ul><ul><li>The elements did not change, just the physical state </li></ul></ul></ul>
  7. 7. Chemical Reaction <ul><li>Have a different end product after the reaction </li></ul><ul><li>Combine 2 compounds and end up with something completely different </li></ul><ul><ul><li>CH 4 + 2O 2 = CO 2 + 2H 2 O </li></ul></ul><ul><ul><ul><li>1 methane molecule + 2 oxygen molecules = 1 carbon dioxide molecule + 2 water molecules </li></ul></ul></ul>
  8. 8. Noble Gases <ul><li>Don’t bond with anything because their outer energy level is full. </li></ul>
  9. 9. Bonding <ul><li>How compounds interact with each other </li></ul>
  10. 10. Ionic Bonding <ul><li>Bond that forms between 2 ions </li></ul><ul><li>Ions have a charge (either + or -) </li></ul><ul><li>The opposite charges attract each other, like magnets </li></ul><ul><li>Example: NaCl (sodium Chloride) </li></ul><ul><ul><li>Na + + Cl - = NaCl </li></ul></ul>
  11. 11. Na Cl + - Transfer the electron NaCl
  12. 12. Covalent Bonding <ul><li>Bonding that occurs when electrons are shared, not gained or lost </li></ul><ul><li>Example: 2H </li></ul><ul><ul><li>Because the outer level is “happy” with 2 electrons, and normally a H atom only has 1 electron in its outer energy level. </li></ul></ul><ul><ul><li>So 2 H atoms get together and share their one electron with each other.  </li></ul></ul><ul><ul><ul><li>Aren’t they nice? </li></ul></ul></ul>
  13. 13. Covalent Bonds <ul><li>Nonmetals hold onto their valence electrons. </li></ul><ul><li>They can’t give away electrons to bond. </li></ul><ul><li>Still want noble gas configuration. </li></ul><ul><li>Get it by sharing valence electrons with each other. </li></ul><ul><li>By sharing both atoms get to count the electrons toward noble gas configuration. </li></ul>
  14. 14. Covalent bonding Fluorine has seven valence electrons <ul><li>A second atom also has seven </li></ul>By sharing electrons … both end with full orbitals 8 Valence electrons 8 Valence electrons F F
  15. 15. Lewis Structures <ul><li>1) Count up total number of valence electrons </li></ul><ul><li>2) Connect all atoms with single bonds </li></ul><ul><li>- “multiple” atoms usually on outside </li></ul><ul><li>- “single” atoms usually in center; </li></ul><ul><li>C always in center, </li></ul><ul><li>H always on outside. </li></ul><ul><li>3) Complete octets on exterior atoms </li></ul><ul><li>(not H, though) </li></ul><ul><li>4) Check </li></ul><ul><li>- valence electrons math with Step 1 </li></ul><ul><li>- all atoms (except H) have an octet; </li></ul><ul><li>if not, try multiple bonds </li></ul><ul><li>- any extra electrons? </li></ul><ul><li>Put on central atom </li></ul>
  16. 16. How to draw them <ul><li>Add up all the valence electrons. </li></ul><ul><li>Count up the total number of electrons to make all atoms happy. </li></ul><ul><li>Subtract. </li></ul><ul><li>Divide by 2 </li></ul><ul><li>Tells you how many bonds - draw them. </li></ul><ul><li>Fill in the rest of the valence electrons to fill atoms up. </li></ul>