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Pudding and Clouds

Pudding and Clouds. Pictures and Notes. Use textbook as second source of information. For info on atom: Pages 105-108 For info on theories and models: pg 8-10. WHAT IS A MODEL?. A model (theory).

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Pudding and Clouds

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  1. Pudding and Clouds Pictures and Notes

  2. Use textbook as second source of information For info on atom: Pages 105-108 For info on theories and models: pg 8-10

  3. WHAT IS A MODEL?

  4. A model (theory) The most accurate visual and written description/explanation of a concept based on all the known facts at the time. A model (theory) must be changed/modified if any new evidence is discovered

  5. HISTORY OF THE ATOMIC MODEL

  6. First recorded use of the term • Democritus (4th century BC) • Universe is made of invisible units called atoms • “unable to be divided” • Movement of atoms caused changes in matter

  7. Democritus

  8. 5 REQUIRED MODELS OF ATOMIC STRUCTURE

  9. 1st model (Billiard Ball) • John Dalton (1808) • English school teacher • All atoms of a given atom are exactly alike • Solid spheres (no parts of atoms) • Revived ancient Greek notion of atom • Atoms of different elements are not exactly the same • Compounds are made up of atoms of 2 or more elements

  10. Billiard Ball model Dalton Atoms are solid spheres (no parts) Neutral Different elements have different atoms

  11. John Dalton

  12. 2nd Model (Plum Pudding) • JJ Thompson • Discovered the existence of electrons • “Plum Pudding” model • “Pudding” solid, positively charged mass • “Raisins” small pieces imbedded within pudding, negatively charged (electrons)

  13. Plum Pudding J.J. Thompson Electrons stuck in solid material

  14. JJ Thompson

  15. 3rd model (Nuclear) Ernst Rutherford His experiments determined that an atom is composed mainly of empty space At the center of an atom is a small, dense, negatively charged nucleus Electrons move around the nucleus Nucleus is still a blob, electrons move

  16. Nuclear model Rutherford Atoms have a nucleus Nucleus is small,dense, and positively charged Electrons move around nucleus

  17. Rutherford

  18. 4th model (solar system) Niels Bohr Electrons can only be found at certain distances from the nucleus These distances are called shells or orbitals Shells are similar to orbits of planets, but on a much smaller scale Motion of electrons is predictable Nucleus is still a single blob

  19. Solar System Model Nucleus is same as before Electrons move in orbits at different distances from nucleus

  20. Niels Bohr

  21. 5th and Current model Nucleus is composed of protons and neutrons Neutrons are the same mass as protons , but have no charge The motion of electrons is generally random, but always a certain distance from the nucleus. One can never know exactly where a specific electron is at a specific point in time. However electrons move within a cloud. Since the boundaries of the cloud are defined, it is known that the electron is somewhere within

  22. Current model Nucleus is composed of neutrons and protons Electrons move about the nucleus in random paths (but keeping the same distance away from nucleus)

  23. Schrödinger

  24. ATOMIC PARTS

  25. What is in an atom?

  26. WHAT ARE THE 3 REGIONS OF ANY ATOMS?

  27. Regions Nucleus: Location of all protons and neutrons Has nearly all of atom’s mass Located at center of atom Electron Cloud: Region where the electrons travel around the nucleus Void: The space between the electron cloud and the nucleus

  28. WHAT’S COMPOSES THE NUCLEUS AND CLOUD?

  29. Answer Protons: Identical in size and mass to a neutron Has a positive electric charge Located in the nucleus Neutrons: Identical in size and mass to a proton Has a no electrical charge Located in nucleus Electrons: Much smaller in size and mass than other components Has a negative charge Orbits the nucleus within a cloud

  30. ELECTRON CLOUD

  31. Electrons and shells Position in a shell is defined by the amount of energy an electron possesses Electrons seek to occupy the shell that requires the least amount of energy

  32. Electron cloud Region where all electrons are found in atom Electrons moving too fast to individually identify, can only define space Electrons are like the moving blades of a fan. You can not really tell the exact position of the blade at any moment of time, but you know the blade is moving within its casing(safety bars)

  33. Electron cloud

  34. ELECTRIC CHARGE

  35. Charge The overall charge of the normal atom is neutral The charge of protons is positive The charge of electrons is negative 1 electron will neutralize 1 proton The number of neutrons in a nucleus does NOT change its charge

  36. Number of electrons For a neutral atom The number of electrons = the number of protons

  37. PARTICLE COMPARISON

  38. Size comparisons of the particles If the nucleus were the size of a mini-marshmallow, the electrons would be moving in a cloud about 100 yards away The neutrons and protons are over 1000 times larger than an electron

  39. Mass comparison If you were an electron weighing 150 lbs, a proton would be about 187,000 lbs, about the weight of a commercial jet

  40. Mass comparison between electron and proton

  41. UNITS OF ATOMIC MASS

  42. Why don’t we use the regular units of mass? The mass of an atom or its parts is incredibly small compared to our scale. Scientific notation (6 x 10 -23lbs) would have to be extensively used, confusion would result Solution was to invent a new unit on the scale of subatomic particles for mass

  43. Atomic Mass Unit • The unit of measurement for atomic mass • 1 atomic mass unit (amu or au) = the mass of one neutron or proton • 1 amu = 1/12th of the mass of the standard carbon atom

  44. WHAT ARE PROTONS, NEUTRONS AND ELECTRONS MADE UP OF?

  45. Parts of Parts • Neutrons and protons are made up of smaller pieces, called quarks • There are six types of quarks called: up, down, charm, strange, truth and beauty Electrons are considered fundamental particles

  46. How do we draw an atom? It would be very confusing to represent the electrons of an atom as a cloud or shell. Easier to draw electrons in orbits. Several electrons can occupy the same orbit or different ones Protons and neutrons are drawn the same except one type will be shaded or colored

  47. Electrons and Protons For the atom to have an overall neutral charge, what must be true about the number of protons and electrons it has?

  48. The Bohr model drawing of an atom Helium Nitrogen

  49. Draw a Bohr model of Beryllium (4 protons, 5 neutrons, 4 electrons) Boron (5 protons, 6 neutrons, 5 electrons) Neon (10 protons, 10 neutrons, 10 electrons)

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