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Chapter 13

Chapter 13. The Structure of the Atom. What do you think atoms are and what do they look like?. Opener - Atoms . How did Democritus define atoms?. Atoms are not all the same, they are undying, and always moving

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Chapter 13

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  1. Chapter 13 The Structure of the Atom

  2. What do you think atoms are and what do they look like? Opener - Atoms

  3. How did Democritus define atoms? • Atoms are not all the same, they are undying, and always moving • All matter is made of indivisible tiny things too small to be seen by the naked eye Democritus – 400 BC

  4. How did Aristotle expand his definition? • Matter is made of atoms and will always exist • He defined the four elements as earth, wind, water and fire Aristotle – 384 BC

  5. What are alchemists? • Scientists who worked on the philosophers stone or the elixir of immortality • Ancient chemistry which led to advances in modern chemistry and the scientific method Alchemists – 500 BC to 1720 AD

  6. How did Lavoisier change the atomic model? • First to name specific elements oxygen and hydrogen • Developed first periodic table with 33 elements Lavoisier - 1777

  7. How did Dalton change it? • Found that elements combine to form compounds • Found that atoms have mass • Started using chemical symbols • Created the billiard ball model Dalton – 1803

  8. How did Thompson change it? • By accident he discovered subatomic particles such as electrons • Developed the plum pudding model Thompson – 1897

  9. Thompson’sPlum Pudding Model

  10. How did Rutherford change it? • Discovered that atoms had an atomic nucleus • Found that the nucleus was positive and that electrons were negative • Also that most of an atom is empty space • Gold foil experiment • Developed the planetary model Rutherford – 1898

  11. Particles were shot at a piece of gold foil which hit the nuclei and scattered Rutherford’sGold Foil Experiment

  12. Rutherford’sPlanetary Model

  13. How did Lewis change it? • Made advances in showing how atoms bond together and how they can share electrons Lewis – 1916

  14. How did Bohr change it? • Began the development of the modern model • Electrons are located outside the nucleus in orbitals • Each orbital has a very specific amount of energy Bohr – 1922

  15. Bohr Model – Carbon Atom

  16. What sub-atomic particles are found in a nucleus? • Protons • Charge: +1 • Symbol: p+ • Neutrons • Charge: 0 • Symbol: n0 Nucleus

  17. What are the properties of electrons? • Found orbiting around the outside of the nucleus • Charge: -1 • Symbol: e- Electrons

  18. The History of the Atom

  19. Person who gives out tickets to traffic court. • Half a dime. • What they do with dead people. • What all that glitters is not. • What you do to cattle that get away. • What a horse has to be if he won’t go for water. • Lone Ranger’s horse. • A really “pressing” thing. • What most lectures are. • Twice a half-nium. • Prisoner who sniffed laughing gas. • Soldier from Troy who only fights after dark. • What a doctor should do for his patients (2 available answers). • Roman streaker who wore shoes with wings. • What I do is none of your _______________! • What the police do to drug houses? • How we refer to the guy who had his stomach removed. • What the Lone Ranger did to his horse Opener - Element Puns

  20. What is an element? • A substance made up of one type of atom • Each atom MUST have the same number of protons, but may have different numbers of electrons (ions) and neutrons (isotopes) The Atom

  21. What is the significance of the atomic number? • Indicates how many protons there are in the element • ONLY way to identify an element Atomic Number

  22. Please find the atomic numbers (number of protons) for: • Hydrogen • Carbon • Silicon • Fluorine • Gold • Potassium • H: 1 • C: 6 • Si: 14 • F: 9 • Au: 79 • K: 19 Atomic Number

  23. How do we figure out the mass of an atom? • Use the atomic mass, which is total mass of all of the sub-atomic pieces • Proton – 1 AMU • Neutron – 1 AMU • Electron – 0 AMU (because its so small) Atomic Mass

  24. How do we figure out how many neutrons are in a nucleus? • Determine the atomic mass • Subtract out the protons (atomic number) • Round DOWN the remaining number (can’t have a part of a neutron) Neutrons

  25. Why don’t we subtract out electrons? • We assume that they have no mass because they are so small Neutrons

  26. Please find the number of neutrons in: • Hydrogen • Carbon • Silicon • Fluorine • Gold • Potassium • H: 0 • C: 6 • Si: 14 • F: 10 • Au: 117 • K: 20 Neutrons

  27. How do we determine the number of electrons in atom? • First determine whether or not the element is neutral or charged (ion) • Neutral – same as the atomic number • Charged – add or subtract the charge to/from the atomic number (Mg2+ or O2-) Electrons

  28. How do I know whether to add or subtract the charge? • Negative charge means you have more electrons  ADD • Positive charge means you have less electrons  SUBTRACT Remember! Electrons are negative so when you subtract them you are subtracting negatives! Electrons

  29. Protons, Neutrons & Electrons

  30. Protons, Neutrons & Electrons – Ions

  31. Where do we place electrons around the nucleus? • Bohr’s orbital model shows us that electrons need to be placed in specific orbitals, shells, or energy levels around the nucleus Electron Placement

  32. How do you place electrons in a Bohr model? • Determine the total number of electrons in the atom or ion • Place the electrons in circular orbitals following the 2-8-8-2 pattern until you have placed all of them Bohr’s Model of an Atom

  33. What is the octet rule? • Atoms “like” to have 8 electrons in the 2nd and 3rd orbitals • 1st orbital is too small to hold 8 electrons • Atoms will react (gain/lose electrons) until they have a FULL outer orbital Bohr’s Model of an Atom

  34. What does carbon’s model look like? • Neutral carbon has 6 electrons • Draw a circular diagram with the following: • 1st orbital – 2 • 2nd orbital – 4 (not full) Bohr’s Model of an Atom

  35. What are valence electrons? • The electrons in the outermost orbital which determine how an element reacts Valence Electrons

  36. Please draw the appropriate Bohr model for: • Li • N • Ne • H • Mg2+ • S2- Bohr’s Model of an Atom

  37. Please draw the appropriate Bohr model for: • Be • Ca • Ar • Na1+ • He0 • H1- • H1+ Opener – Bohr Model Review

  38. How do Lewis dot diagrams simplify Bohr diagrams? • Dot diagrams only show the outer orbital which holds the valence electrons • Ex. Carbon Lewis Dot Diagrams

  39. Please draw the appropriate Lewis dot diagram for: • C • O • F • H • Be2+ • Cl1- Lewis Dot Diagrams

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